HVAC Vacuum Testing
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From: Ball Ground, GA
HVAC Vacuum Testing
Perhaps this would be a good point to insert a test method that can save a lot of hassle in testing the HVAC vacuum system on the later automatic systems.
First, look under the hood at the power brake booster, and find the little vacuum line running off of the large vacuum check valve. A few inches down that line is a black/blue drum - this is the vacuum system check valve. With the engine running, check the vacuum on the line going into the check valve, and the vacuum out of the check valve - there should be only about 1" less out of the check valve, and the hiss should be very similar.
A few more inches down the line should be a four-way rubber cross. Check it for splits and leaks. One leg is usually plugged, one runs toward the left front fender, and one black line runs into the firewall.
Check the line going to the fender for leaks - it will take a LOT of pumps to pump this down, as it runs to the vacuum reservoir, and on earlier cars, the cruise control servo. You can use the engine to pump it down, and try to switch the line to the vacuum tester as quickly as possible to make this easier.
If the vacuum source and reservoir are good, remove the console side panel on the driver's (USA) side. Look just by the driver's right ankle, and find a bundle of colored plastic lines. These lines run to/from the vacuum system valve manifold, which is just visible mounted in front of the radio.
The black line is the main supply line, and the point where it plugs into the end of the monifold is visible. Make sure that it is plugged into the manifold. Remove it, and crank the engine. There should be at least 15" of vacuum on the black line. Replace it and shut the engine off.
Using a sharp knife, cut the orange line that feeds the central vent actuator (this is the most common failure point in the system). Using a MityVac or similar tool (or suck on it if you don't have anything else!), make certain that the line that runs up to the actuator will hold vacuum. If it does, use a rubber tube to reconnect the cut ends of the orange line. If the line to the dash doesn't hold vacuum, plug the line that comes from the manifold - no need to plug the end that runs up in the dash.
Repeat on the yellow, green and blue lines.
The white line feeds the heater valve - you don't want to just plug it, you want to have the heater valve working. If the white line doesn't hold vacuum, remove the air cleaner housing and check the heater valve. If it doesn't hold vacuum, replace it - it's cheap, about $12. The black side goes toward the block.
Keep an eye out for crushed, collapsed, or broken vacuum lines as you work on various areas of the car.
When you finish, and have no vacuum leaks, the HVAC system should work much more efficiently.
When you get ambitious, you can order new vacuum actuators to replace the leakers, and start the major disassembly needed to replace them.
First, look under the hood at the power brake booster, and find the little vacuum line running off of the large vacuum check valve. A few inches down that line is a black/blue drum - this is the vacuum system check valve. With the engine running, check the vacuum on the line going into the check valve, and the vacuum out of the check valve - there should be only about 1" less out of the check valve, and the hiss should be very similar.
A few more inches down the line should be a four-way rubber cross. Check it for splits and leaks. One leg is usually plugged, one runs toward the left front fender, and one black line runs into the firewall.
Check the line going to the fender for leaks - it will take a LOT of pumps to pump this down, as it runs to the vacuum reservoir, and on earlier cars, the cruise control servo. You can use the engine to pump it down, and try to switch the line to the vacuum tester as quickly as possible to make this easier.
If the vacuum source and reservoir are good, remove the console side panel on the driver's (USA) side. Look just by the driver's right ankle, and find a bundle of colored plastic lines. These lines run to/from the vacuum system valve manifold, which is just visible mounted in front of the radio.
The black line is the main supply line, and the point where it plugs into the end of the monifold is visible. Make sure that it is plugged into the manifold. Remove it, and crank the engine. There should be at least 15" of vacuum on the black line. Replace it and shut the engine off.
Using a sharp knife, cut the orange line that feeds the central vent actuator (this is the most common failure point in the system). Using a MityVac or similar tool (or suck on it if you don't have anything else!), make certain that the line that runs up to the actuator will hold vacuum. If it does, use a rubber tube to reconnect the cut ends of the orange line. If the line to the dash doesn't hold vacuum, plug the line that comes from the manifold - no need to plug the end that runs up in the dash.
Repeat on the yellow, green and blue lines.
The white line feeds the heater valve - you don't want to just plug it, you want to have the heater valve working. If the white line doesn't hold vacuum, remove the air cleaner housing and check the heater valve. If it doesn't hold vacuum, replace it - it's cheap, about $12. The black side goes toward the block.
Keep an eye out for crushed, collapsed, or broken vacuum lines as you work on various areas of the car.
When you finish, and have no vacuum leaks, the HVAC system should work much more efficiently.
When you get ambitious, you can order new vacuum actuators to replace the leakers, and start the major disassembly needed to replace them.
Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
summer is here, get your AC working
------------------------------------
Test Point 1 - SENSOR CIRCUIT (Ohmmeter)
1. Total Sensor Circuit
The entire sensor circuit can be checked for breaks on the control unit operating motor after removing the footwell shelf on the driver's side.
Testing
Pull off 12-pin plug on the control unit operating motor.
Connect ohmmeter (range: x 100) on plug terminals 4 (yellow) and 12 (yellow).
Ohmmeter should display some resistance. Move temperature switch from 18°to 30°to 18°.
The displayed resistance value must change (approx. 1000 ohms). No change in test value - see section 1.4.
If ohmmeter shows infinite ohms, there is a break in the sensor circuit.
Note: Breaks could be on wire connections in plug, on plug connections, on inside or outside sensor and on the control switch.
1.2 Outside Sensor
The outside temperature sensor is located front left in the alternator's cooling air hose.
Electric connection is made with a 2-pin plug in the left headlight housing and a 4-pin flat male plug behind the right center console trim panel.
Testing
Remove trim panel on right side of center console.
Disconnect 4-pin plug (term. 3/4 both with yellow wire).
Connect ohmmeter (range: x 10) on term. 3 (yellow) and 4 (yellow) on socket end of plug.
Ohmmeter should display following values:
approx. 933 ohms at 0 °C
approx. 588 ohms at 20 °C
approx. 457 ohms at 30 °C
Important: To change the resistance, the cooling air hose can be disconnected on the alternator and air blown into the hose with a hot air blower - the displayed value must drop.
Repeat tests on the sensor itself (plug in headlight housing), if test values are not reached.
(Possibly high resistance, loose wires, etc.)
Display of infinite ohms indicates a break.
Note: If the sensor wire has a break, the system will be regulated in heating direction and can no longer be regulated with the temperature switch (18 - 30 °C).
If the sensor has a short, the system will be regulated in warm direction, but only half of the control distance.
1.3 Inside Sensor
The inside temperature sensor is located in the sensor housing (to the right of the center nozzle) in the draft of a small blower. The electric connection is made with a 4-pin flat male plug behind the right center console trim panel.
Testing
Remove trim panel on right side of center console.
Disconnect 4-pin flat male plug (term. 1/2 both with yellow wire).
Connect ohmmeter (range: x 100) on plug pins of term. 1 and 2 (both yellow).
Ohmmeter must display the following values.
approx. 2570 ohms at 20 °C
approx. 2220 ohms at 25 °C
approx. 1900 ohms at 30 °C
Important: The test value measured in the sensor housing must drop by heating up the sensor resistor with a hot air blower. Replace the sensor, if there is not display or no change in resistance. Repeat this test before installing a new sensor.
Blower Test
Connect plug.
Turn on ignition. Set program switch optionally to
The sensor blower must be running!
Place a small piece of paper on the inlet opening or, if you smoke and smoking is permitted, blow cigarette smoke against the intake opening.
If the paper is not held or the smoke not drawn in, check whether blower is running or wire has a break or power supply is missing.
Note: If the sensor wire has a break, the system will be regulated in heating direction and it can no longer be regulated with the temperature switch (18 - 30 °C).
If the sensor has a short, the system will be regulated in cold direction (not in 30°position).
If the sensor blower does not run, even only sometimes, there will be very sluggish temperature regulation in the passenger compartment.
1.4 Temperature Adjusting Potentiometer in Control Switch
A potentiometer, which is adjusted by the temperature switch, is installed in the control switch.
a) Test
Remove trim panel on right side of center console.
Disconnect 4-pin plug of inside sensor. Connect ohmmeter (range: x 10) on socket end term. 1 (yellow).
Temp. lever at 18 °C = approx. 760 ±100 ohms
Temp. lever at 30 °C = approx. 1760 ±100 ohms
It is important, that the resistance value changes by approx. 1000 ohms each time.
Remove control switch, if values are not reached or there is no change in resistance between 18 °C - 30 °C - 18°C.
b) Test
Connect ohmmeter on platinum paths 13 and 14 of the platinum connection. Repeat test described above.
No display - replace control switch.
Display - break in wire.
1.5 Control Unit - Operating Motor
See nominal functions in point A.
It is recommended to connect a new part for comparison, if there is no function and the sensor circuit (test points 1.1 to 1.4) is okay. If the operating motor crank moves as described in point A or if the crank moves when changing the temperature of the inside or outside sensor (control switch/temperature switch in position A), it can be assumed that the installed operating motor is faulty.
------------------------------------
Test Point 1 - SENSOR CIRCUIT (Ohmmeter)
1. Total Sensor Circuit
The entire sensor circuit can be checked for breaks on the control unit operating motor after removing the footwell shelf on the driver's side.
Testing
Pull off 12-pin plug on the control unit operating motor.
Connect ohmmeter (range: x 100) on plug terminals 4 (yellow) and 12 (yellow).
Ohmmeter should display some resistance. Move temperature switch from 18°to 30°to 18°.
The displayed resistance value must change (approx. 1000 ohms). No change in test value - see section 1.4.
If ohmmeter shows infinite ohms, there is a break in the sensor circuit.
Note: Breaks could be on wire connections in plug, on plug connections, on inside or outside sensor and on the control switch.
1.2 Outside Sensor
The outside temperature sensor is located front left in the alternator's cooling air hose.
Electric connection is made with a 2-pin plug in the left headlight housing and a 4-pin flat male plug behind the right center console trim panel.
Testing
Remove trim panel on right side of center console.
Disconnect 4-pin plug (term. 3/4 both with yellow wire).
Connect ohmmeter (range: x 10) on term. 3 (yellow) and 4 (yellow) on socket end of plug.
Ohmmeter should display following values:
approx. 933 ohms at 0 °C
approx. 588 ohms at 20 °C
approx. 457 ohms at 30 °C
Important: To change the resistance, the cooling air hose can be disconnected on the alternator and air blown into the hose with a hot air blower - the displayed value must drop.
Repeat tests on the sensor itself (plug in headlight housing), if test values are not reached.
(Possibly high resistance, loose wires, etc.)
Display of infinite ohms indicates a break.
Note: If the sensor wire has a break, the system will be regulated in heating direction and can no longer be regulated with the temperature switch (18 - 30 °C).
If the sensor has a short, the system will be regulated in warm direction, but only half of the control distance.
1.3 Inside Sensor
The inside temperature sensor is located in the sensor housing (to the right of the center nozzle) in the draft of a small blower. The electric connection is made with a 4-pin flat male plug behind the right center console trim panel.
Testing
Remove trim panel on right side of center console.
Disconnect 4-pin flat male plug (term. 1/2 both with yellow wire).
Connect ohmmeter (range: x 100) on plug pins of term. 1 and 2 (both yellow).
Ohmmeter must display the following values.
approx. 2570 ohms at 20 °C
approx. 2220 ohms at 25 °C
approx. 1900 ohms at 30 °C
Important: The test value measured in the sensor housing must drop by heating up the sensor resistor with a hot air blower. Replace the sensor, if there is not display or no change in resistance. Repeat this test before installing a new sensor.
Blower Test
Connect plug.
Turn on ignition. Set program switch optionally to
The sensor blower must be running!
Place a small piece of paper on the inlet opening or, if you smoke and smoking is permitted, blow cigarette smoke against the intake opening.
If the paper is not held or the smoke not drawn in, check whether blower is running or wire has a break or power supply is missing.
Note: If the sensor wire has a break, the system will be regulated in heating direction and it can no longer be regulated with the temperature switch (18 - 30 °C).
If the sensor has a short, the system will be regulated in cold direction (not in 30°position).
If the sensor blower does not run, even only sometimes, there will be very sluggish temperature regulation in the passenger compartment.
1.4 Temperature Adjusting Potentiometer in Control Switch
A potentiometer, which is adjusted by the temperature switch, is installed in the control switch.
a) Test
Remove trim panel on right side of center console.
Disconnect 4-pin plug of inside sensor. Connect ohmmeter (range: x 10) on socket end term. 1 (yellow).
Temp. lever at 18 °C = approx. 760 ±100 ohms
Temp. lever at 30 °C = approx. 1760 ±100 ohms
It is important, that the resistance value changes by approx. 1000 ohms each time.
Remove control switch, if values are not reached or there is no change in resistance between 18 °C - 30 °C - 18°C.
b) Test
Connect ohmmeter on platinum paths 13 and 14 of the platinum connection. Repeat test described above.
No display - replace control switch.
Display - break in wire.
1.5 Control Unit - Operating Motor
See nominal functions in point A.
It is recommended to connect a new part for comparison, if there is no function and the sensor circuit (test points 1.1 to 1.4) is okay. If the operating motor crank moves as described in point A or if the crank moves when changing the temperature of the inside or outside sensor (control switch/temperature switch in position A), it can be assumed that the installed operating motor is faulty.
Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Test Point 2- COMPRESSOR MAGNETIC CLUTCH
2. Compressor Magnetic Clutch (Test Lamp)
Turn on ignition.
Set temperature switch to 18 °C.
Set program switch to any position. Press AC switch.
The magnetic clutch must be heard (click) when pressing the AC switch.
Connect test lamp on ground (engine/body), if the clutch does not function.
Test lamp must come on at following test points.
a) Compressor clutch plug (in front of camshaft cover on right side).
b) Connection on electric air valve (on right engine cross member).
c) Socket end term. 9 of engine multiple-pin plug (in engine compartment, right).
d) On both connections of low pressure switch (on side of filter drier).
e) On CEL plug M 12, K 21 and G 21.
f) On both connections of icing-up protection switch (on blower housing).
g) On term. 2 (purple/yellow) and term. 1 (red/white) of 4-pin plug for outside sensor (center console).
h) On term. 6 (purple/yellow) and term. 5 (red/white) and term. 7 (green/blue) of connected control switch plug.
i) CEL fuse no.17.
Note: This test only covers the electric activation of the compressor clutch - perform trouble-shooting procedures step by step!
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2. Compressor Magnetic Clutch (Test Lamp)
Turn on ignition.
Set temperature switch to 18 °C.
Set program switch to any position. Press AC switch.
The magnetic clutch must be heard (click) when pressing the AC switch.
Connect test lamp on ground (engine/body), if the clutch does not function.
Test lamp must come on at following test points.
a) Compressor clutch plug (in front of camshaft cover on right side).
b) Connection on electric air valve (on right engine cross member).
c) Socket end term. 9 of engine multiple-pin plug (in engine compartment, right).
d) On both connections of low pressure switch (on side of filter drier).
e) On CEL plug M 12, K 21 and G 21.
f) On both connections of icing-up protection switch (on blower housing).
g) On term. 2 (purple/yellow) and term. 1 (red/white) of 4-pin plug for outside sensor (center console).
h) On term. 6 (purple/yellow) and term. 5 (red/white) and term. 7 (green/blue) of connected control switch plug.
i) CEL fuse no.17.
Note: This test only covers the electric activation of the compressor clutch - perform trouble-shooting procedures step by step!
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Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Test Point 3 - BLOWER
3. Blower (Test Lamp/Voltmeter)
Turn on ignition.
Set program switch to
Blower should be running at maximum speed. If not, check fuse no.17.
Blower not running, check:
a) CEL plug G 15: approx. 12 V (control switch okay).
b) Pull off DEF relay VIII, bridge term. 30 and 87 - blower running or approx. 12 V on CEL plug G 22 (check relay socket/relay).
c) The 2-pin blower plug must have approx. 12 V (blower motor); set control switch to DASH.
d) Approx. 12 V on CEL plug G 14 (control switch okay).
e) Pull off blower relay X, bridge term. 30 and 87 - blower running or approx. 12 V on CEL plug G 21 (check relay socket/relay).
f) There must be between 4 and approx. 12 V on the 2-pin blower plug (depending on speed switch position).
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3. Blower (Test Lamp/Voltmeter)
Turn on ignition.
Set program switch to
Blower should be running at maximum speed. If not, check fuse no.17.
Blower not running, check:
a) CEL plug G 15: approx. 12 V (control switch okay).
b) Pull off DEF relay VIII, bridge term. 30 and 87 - blower running or approx. 12 V on CEL plug G 22 (check relay socket/relay).
c) The 2-pin blower plug must have approx. 12 V (blower motor); set control switch to DASH.
d) Approx. 12 V on CEL plug G 14 (control switch okay).
e) Pull off blower relay X, bridge term. 30 and 87 - blower running or approx. 12 V on CEL plug G 21 (check relay socket/relay).
f) There must be between 4 and approx. 12 V on the 2-pin blower plug (depending on speed switch position).
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Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Test Point 4 - FLAP CONTROL
4. Flap Control (Test Lamp)
Remove control switch; plug remains connected.
Run engine at idle speed and set blower switch to maximum speed.
4.1 Circulating Air Flap
Program switch in off position.
Control switch plug term. 9 and 10 must have approx. 12 V and circulating air flap must be open (air circulated).
If not: Check 6-pin plug term. 1 (black/white) (center console) approx. 12 V.
Check voltage on blue connection of circulating air solenoid valve (approx. 12 V).
Replace solenoid valve, if vacuum is okay and flap vacuum box works.
Circulating air flap must close when setting program switch to DASH (fresh air).
4.2 Defroster Flap
Program switch in OFF/DASH/FOOTWELL.
Approx. 12 V on control switch term. 2 and 10; defroster flap must be closed.
If not: Check 6-pin plug term. 1 (black/white) (center console) (approx. 12 V).
Check for approx. 12 V on green connection of defroster solenoid valve.
Replace solenoid valve if vacuum is okay and flap vacuum box works.
Defroster flap must be open, when program switch is set to BI/WINDSHIELD/DEF.
4.3 Footwell Flap
Set program switch to BI/WINDSHIELD.
There should be approx. 12 V on control switch plug term. 1 and 10; footwell flap must be open.
If not: Check 6-pin plug term. 1 (black/white) (center console) (approx. 12 V).
Check for approx. 12 V on yellow connection of footwell solenoid valve.
Replace solenoid valve, if vacuum is okay and flap vacuum box works.
Footwell flap must close, when program switch is moved to OFF/DASH/BI/DEF
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4. Flap Control (Test Lamp)
Remove control switch; plug remains connected.
Run engine at idle speed and set blower switch to maximum speed.
4.1 Circulating Air Flap
Program switch in off position.
Control switch plug term. 9 and 10 must have approx. 12 V and circulating air flap must be open (air circulated).
If not: Check 6-pin plug term. 1 (black/white) (center console) approx. 12 V.
Check voltage on blue connection of circulating air solenoid valve (approx. 12 V).
Replace solenoid valve, if vacuum is okay and flap vacuum box works.
Circulating air flap must close when setting program switch to DASH (fresh air).
4.2 Defroster Flap
Program switch in OFF/DASH/FOOTWELL.
Approx. 12 V on control switch term. 2 and 10; defroster flap must be closed.
If not: Check 6-pin plug term. 1 (black/white) (center console) (approx. 12 V).
Check for approx. 12 V on green connection of defroster solenoid valve.
Replace solenoid valve if vacuum is okay and flap vacuum box works.
Defroster flap must be open, when program switch is set to BI/WINDSHIELD/DEF.
4.3 Footwell Flap
Set program switch to BI/WINDSHIELD.
There should be approx. 12 V on control switch plug term. 1 and 10; footwell flap must be open.
If not: Check 6-pin plug term. 1 (black/white) (center console) (approx. 12 V).
Check for approx. 12 V on yellow connection of footwell solenoid valve.
Replace solenoid valve, if vacuum is okay and flap vacuum box works.
Footwell flap must close, when program switch is moved to OFF/DASH/BI/DEF
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Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
May 10, 1991
Model Group
928 S/S4/GT 8
Part Identifier Number
8702 9101
Subject:
A/C Setting Motor Testing
ATTENTION: Service Manager/Service Technician
Models Affected: 928 S/S4/GT
Concern: 928 Workshop Manual: Testing climate control setting motor procedure incorrect.
Workshop Manual Correction: 928 Workshop Manual, Part Number WKD 481 621, Volume IV, page 87-113.
The statement: "Remove plug 1 to check switching functions of setting motor" is not correct
Test points 6 through 11 must be performed with plug 1 connected.
Please correct your Workshop Manuals to read as follows:
Check switching functions of setting motor with plug 1 connected. Probe wires from back of plug.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/yltype.gif" border="0" alt="[typing]" />
Model Group
928 S/S4/GT 8
Part Identifier Number
8702 9101
Subject:
A/C Setting Motor Testing
ATTENTION: Service Manager/Service Technician
Models Affected: 928 S/S4/GT
Concern: 928 Workshop Manual: Testing climate control setting motor procedure incorrect.
Workshop Manual Correction: 928 Workshop Manual, Part Number WKD 481 621, Volume IV, page 87-113.
The statement: "Remove plug 1 to check switching functions of setting motor" is not correct
Test points 6 through 11 must be performed with plug 1 connected.
Please correct your Workshop Manuals to read as follows:
Check switching functions of setting motor with plug 1 connected. Probe wires from back of plug.
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Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
CHECKING OPERATING SWITCH
Note: With operating switch removed and all connections made, use a voltmeter to test voltages at the 15- pole plug.
Switch on ignition.
Connect voltmeter to terminal 1 (plus) and terminal 4 (minus). Air-distribution slide at bottom and bottom/top. Reading: Battery voltage.
Connect voltmeter to terminal 2 and terminal 4. Air-distribution slide at off, center and bottom. Reading: Battery voltage
Connect voltmeter to terminal 3 and terminal 4. Switch on position lights. Reading: Battery voltage.
Connect voltmeter to terminal 5 and terminal 4. Air-distribution slide at centre, bottom, bottom/top, top and defrost. Reading: Battery voltage. If no voltage is registered, check whether fresh-air blower relay switches. If the fresh-air blower relay does not switch, test the signal at terminal 86. Connect voltmeter to terminal 15 and terminal 4 of operating switch. Air-distribution slide at the same positions. Reading: Battery voltage.
Connect voltmeter to terminal 7 and terminal 4. Air-distribution slide at center, bottom, bottom/top and defrost. Switch on auxiliary air conditioner. Reading: Battery voltage If no voltage is registered, check air-conditioner switch.
Connect voltmeter to terminal 6 and terminal 4. Air-distribution slide at center, bottom, bottom/top and top. Switch on auxiliary air conditioner. Reading: Battery voltage.
Connect voltmeter to terminal 8 and terminal 4. Air-distribution slide to center, bottom, bottom/top and top. Temperature regulator slide at 18. Reading: Battery voltage Move temperature regulator slide to 27. The setting motor moves toward heating. At 10%, the voltage in interrupted.
Connect voltmeter to terminal 9 and terminal 4. Air-distribution slide at off. Reading: Battery voltage
Leave voltmeter connected to terminal 9 and terminal 4. Air-distribution slide at center, bottom, bottom/top and top. Switch on air conditioner. Temperature regulator slide at 18. Display: Battery voltage. Set temperature regulator slide to 27. The setting motor moves toward heating. Voltage is interrupted at 10%.
Connect voltmeter to terminal 10 and terminal 4. Reading: Battery voltage
Connect voltmeter to terminal 11 and terminal 4. Air-distribution slide at defrost. Reading: Battery voltage The fresh-air blower must run at top speed. If not, check defrost relay or fresh-air blower.
Connect voltmeter to terminal 12 and terminal 4. Air-distribution slide at center, bottom, bottom/top and top. Temperature regulator slide at 18. Reading: Battery voltage Move temperature regulator slide to 27. The setting motor moves toward heating. Voltage is interrupted at 20%.
Connect voltmeter to terminal 15 and terminal 4. Air-distribution slide at center, bottom, bottom/top, top and defrost. Reading: Battery voltage
Disconnect cable plug. Connect ohmmeter to terminal 13 and terminal 14. Move temperature regulator slide to 18. Reading: approx. 750 ±100 Ohm Move temperature regulator slide to 30. Reading: approx. 1750 ±100 Ohm Note:
The resistance must change by approx. 1000 Ohm.
If the values at terminals 1, 2, 6, 9, 11, 12, 13, 14 and 15 are not attained, the operating switch is defective and must be replaced.
If the values are not attained at the other terminals, check the wiring using the circuit diagram.
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Note: With operating switch removed and all connections made, use a voltmeter to test voltages at the 15- pole plug.
Switch on ignition.
Connect voltmeter to terminal 1 (plus) and terminal 4 (minus). Air-distribution slide at bottom and bottom/top. Reading: Battery voltage.
Connect voltmeter to terminal 2 and terminal 4. Air-distribution slide at off, center and bottom. Reading: Battery voltage
Connect voltmeter to terminal 3 and terminal 4. Switch on position lights. Reading: Battery voltage.
Connect voltmeter to terminal 5 and terminal 4. Air-distribution slide at centre, bottom, bottom/top, top and defrost. Reading: Battery voltage. If no voltage is registered, check whether fresh-air blower relay switches. If the fresh-air blower relay does not switch, test the signal at terminal 86. Connect voltmeter to terminal 15 and terminal 4 of operating switch. Air-distribution slide at the same positions. Reading: Battery voltage.
Connect voltmeter to terminal 7 and terminal 4. Air-distribution slide at center, bottom, bottom/top and defrost. Switch on auxiliary air conditioner. Reading: Battery voltage If no voltage is registered, check air-conditioner switch.
Connect voltmeter to terminal 6 and terminal 4. Air-distribution slide at center, bottom, bottom/top and top. Switch on auxiliary air conditioner. Reading: Battery voltage.
Connect voltmeter to terminal 8 and terminal 4. Air-distribution slide to center, bottom, bottom/top and top. Temperature regulator slide at 18. Reading: Battery voltage Move temperature regulator slide to 27. The setting motor moves toward heating. At 10%, the voltage in interrupted.
Connect voltmeter to terminal 9 and terminal 4. Air-distribution slide at off. Reading: Battery voltage
Leave voltmeter connected to terminal 9 and terminal 4. Air-distribution slide at center, bottom, bottom/top and top. Switch on air conditioner. Temperature regulator slide at 18. Display: Battery voltage. Set temperature regulator slide to 27. The setting motor moves toward heating. Voltage is interrupted at 10%.
Connect voltmeter to terminal 10 and terminal 4. Reading: Battery voltage
Connect voltmeter to terminal 11 and terminal 4. Air-distribution slide at defrost. Reading: Battery voltage The fresh-air blower must run at top speed. If not, check defrost relay or fresh-air blower.
Connect voltmeter to terminal 12 and terminal 4. Air-distribution slide at center, bottom, bottom/top and top. Temperature regulator slide at 18. Reading: Battery voltage Move temperature regulator slide to 27. The setting motor moves toward heating. Voltage is interrupted at 20%.
Connect voltmeter to terminal 15 and terminal 4. Air-distribution slide at center, bottom, bottom/top, top and defrost. Reading: Battery voltage
Disconnect cable plug. Connect ohmmeter to terminal 13 and terminal 14. Move temperature regulator slide to 18. Reading: approx. 750 ±100 Ohm Move temperature regulator slide to 30. Reading: approx. 1750 ±100 Ohm Note:
The resistance must change by approx. 1000 Ohm.
If the values at terminals 1, 2, 6, 9, 11, 12, 13, 14 and 15 are not attained, the operating switch is defective and must be replaced.
If the values are not attained at the other terminals, check the wiring using the circuit diagram.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/yltype.gif" border="0" alt="[typing]" />
Trending Topics
Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Tools - Compressor Seal Replacement
90porsche03
April 20, 1990
Subject: A/C Compressor Tools
Model Group
N/A N/A
Part Identifer Number
N/A 9003
Below are listed those special Porsche tools needed to correctly perform the air conditioner compressor seal replacement on 1984 and later 911 and 944 models and on the Nippondenso (6 Cylinder) compressor for 928 models. Although information concerning these tools did not get printed in the new Service Tools and Equipment binder, they are minimum requirement tools and have been shipped to all Porsche dealers.
Order Model
Number Description Application
PNA 721 010 Seal puller 911, 944, 928
PNA 721 011 Friction washer puller 911, 944, 928
PNA 721 012 Thrust member 911, 944, 928
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90porsche03
April 20, 1990
Subject: A/C Compressor Tools
Model Group
N/A N/A
Part Identifer Number
N/A 9003
Below are listed those special Porsche tools needed to correctly perform the air conditioner compressor seal replacement on 1984 and later 911 and 944 models and on the Nippondenso (6 Cylinder) compressor for 928 models. Although information concerning these tools did not get printed in the new Service Tools and Equipment binder, they are minimum requirement tools and have been shipped to all Porsche dealers.
Order Model
Number Description Application
PNA 721 010 Seal puller 911, 944, 928
PNA 721 011 Friction washer puller 911, 944, 928
PNA 721 012 Thrust member 911, 944, 928
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/yltype.gif" border="0" alt="[typing]" />
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Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Service Precautions
The Clean Air Act Amendment of 1990 requires that Freon be recovered when accessing the air conditioning circuit and that technicians hold a refrigerant recovery and handling certification.
The Ozone Layer
A thin layer of ozone molecules, located 10 to 30 miles above the earth, form a protective cover by absorbing a portion of the ultraviolet (UV) radiation emitted from the Sun.
Ozone Depletion
Scientific research performed over the past 15 years links the release of chlorofluorocarbons (CFC)s, also know by the trade name Freon) into the atmosphere to ozone depletion. When CFCs are released into the atmosphere, they eventually reach the ozone layer located in the stratosphere where they react with and destroy ozone molecules.
Harmful Effects
Ozone depletion and the corresponding increase in UV radiation has been shown to lead to higher incidents of cancer as well as global warming. When viewed from a global perspective, ozone depletion holds an enormous potential for damage.
Upper Level vs. Ground Level Ozone
Confusion often arises when we hear about the necessity of the ozone layer and ground level ozone. The ozone layer existing high above the earth is beneficial but the same compound, when located at ground level, is harmful to humans, animals, crops and vegetation.
Ground level ozone is a component of smog and forms when hydrocarbons (HC) react with nitrogen oxides (NOx) in the presence of sunlight and heat.
Montreal Protocol
In response to the growing body of evidence demonstrating the detrimental effects of (CFC)s, 24 countries and the European community met in Montreal, Canada, in 1987 to establish standards for the control of (CFC)s. Since that time, a total of 132 countries have become signatories to this agreement leading to an end of production of R12 in December, 1995, in all developed countries.
As established by the Montreal Protocol, R12 production in developed countries has ceased.
Clean Air Act
The United States Congress, acting in response to the Montreal Protocol, banned production of (CFC)s by the year 2000. Congress also amended the Clean Air Act in an effort to control both the production and use of (CFC)s for refrigerant applications including mobile vehicle air conditioning systems.
Alternative Refrigerants
The introduction of alternative refrigerants, primarily the hydrofluorocarbon (HFC) 134a, aims at preventing further ozone layer depletion. Because 134a is chlorine free, it is deemed ozone safe.
Technician Certification
Organizations providing technician refrigerant recovery and recycling certification include:
National Institute for Automotive Service Excellence (ASE)
13505 Dulles Technology Drive, Suite 2
Herndon, VA 22071-3421
Phone: (703) 713-3800
Fax: (703) 713-0727
<a href="http://www.asecert.org/" target="_blank">http://www.asecert.org/</a>
International Mobile Air Conditioning Association (IMACA)
P.O. Box 9000
Fort Worth, TX 76147-2000
Phone: (817) 338-1100
Fax: (817) 338-1451
Mobile Air Conditioning Society (MACS) Worldwide
P.O. Box 100
East Greenville, PA 18041
Phone: 215-679-2220
Fax: 215-541-4635
<a href="http://www.macsw.org/" target="_blank">http://www.macsw.org/</a>
HAPPY HUNTING.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />
The Clean Air Act Amendment of 1990 requires that Freon be recovered when accessing the air conditioning circuit and that technicians hold a refrigerant recovery and handling certification.
The Ozone Layer
A thin layer of ozone molecules, located 10 to 30 miles above the earth, form a protective cover by absorbing a portion of the ultraviolet (UV) radiation emitted from the Sun.
Ozone Depletion
Scientific research performed over the past 15 years links the release of chlorofluorocarbons (CFC)s, also know by the trade name Freon) into the atmosphere to ozone depletion. When CFCs are released into the atmosphere, they eventually reach the ozone layer located in the stratosphere where they react with and destroy ozone molecules.
Harmful Effects
Ozone depletion and the corresponding increase in UV radiation has been shown to lead to higher incidents of cancer as well as global warming. When viewed from a global perspective, ozone depletion holds an enormous potential for damage.
Upper Level vs. Ground Level Ozone
Confusion often arises when we hear about the necessity of the ozone layer and ground level ozone. The ozone layer existing high above the earth is beneficial but the same compound, when located at ground level, is harmful to humans, animals, crops and vegetation.
Ground level ozone is a component of smog and forms when hydrocarbons (HC) react with nitrogen oxides (NOx) in the presence of sunlight and heat.
Montreal Protocol
In response to the growing body of evidence demonstrating the detrimental effects of (CFC)s, 24 countries and the European community met in Montreal, Canada, in 1987 to establish standards for the control of (CFC)s. Since that time, a total of 132 countries have become signatories to this agreement leading to an end of production of R12 in December, 1995, in all developed countries.
As established by the Montreal Protocol, R12 production in developed countries has ceased.
Clean Air Act
The United States Congress, acting in response to the Montreal Protocol, banned production of (CFC)s by the year 2000. Congress also amended the Clean Air Act in an effort to control both the production and use of (CFC)s for refrigerant applications including mobile vehicle air conditioning systems.
Alternative Refrigerants
The introduction of alternative refrigerants, primarily the hydrofluorocarbon (HFC) 134a, aims at preventing further ozone layer depletion. Because 134a is chlorine free, it is deemed ozone safe.
Technician Certification
Organizations providing technician refrigerant recovery and recycling certification include:
National Institute for Automotive Service Excellence (ASE)
13505 Dulles Technology Drive, Suite 2
Herndon, VA 22071-3421
Phone: (703) 713-3800
Fax: (703) 713-0727
<a href="http://www.asecert.org/" target="_blank">http://www.asecert.org/</a>
International Mobile Air Conditioning Association (IMACA)
P.O. Box 9000
Fort Worth, TX 76147-2000
Phone: (817) 338-1100
Fax: (817) 338-1451
Mobile Air Conditioning Society (MACS) Worldwide
P.O. Box 100
East Greenville, PA 18041
Phone: 215-679-2220
Fax: 215-541-4635
<a href="http://www.macsw.org/" target="_blank">http://www.macsw.org/</a>
HAPPY HUNTING.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />
Intermediate
Joined: Jun 2002
Posts: 40
Likes: 0
From: georgia
good stuff steve and wally, for safty in electrical testing on and around these high dollar componants i highly suggest the use of a volt meter rather than a test light. 10 megohm impedence test lights are available also. but the volt meter also can show low voltages where a test light may not, this can help to trace and find poor grounds, bad relays or just bad contacts at plugs or splices. there seems to be a growing list of electrical gremlins as these cars age.
just a quick note on freon. dupont had sole patent rights on r12 since 1959, these rights expire after 30 years, funny how the cfc issue started about then. and better yet guess who happened to have a new replacment ready and holds sole patent rights on r134 for the next thirty years. better still, in my trade magazines they are saying that 134 is less ozone friendly than r12 ever was. just makes you wonder what makes the world tic these days eh. joel
just a quick note on freon. dupont had sole patent rights on r12 since 1959, these rights expire after 30 years, funny how the cfc issue started about then. and better yet guess who happened to have a new replacment ready and holds sole patent rights on r134 for the next thirty years. better still, in my trade magazines they are saying that 134 is less ozone friendly than r12 ever was. just makes you wonder what makes the world tic these days eh. joel
Burning Brakes
Joined: Jul 2001
Posts: 1,051
Likes: 1
THOM’S A/C SERVICE ESSENTIALS:
RULES:
1. If you open the system: Replace the dryer. Vacuum the moisture out.
2. If you convert to R134A, flush the old oil & contaminants out. Change o-rings. Oil o-rings before installation.
3. If o-rings are ever exposed, replace them with new ones.
RECOMMENDATIONS:
1. VACUUM GREMLINS ARE…STRANGER THAN FICTION! Fix them all before you try anything else.
2. With inexpensive R12 compatible refrigerants available, it may not be so good to convert to R134A. However, people have obtained very good results in 928s with R134A. See REFRIGERANTS below.
3. If you open the system, flush it too. By now it may have 2 or 3 times over the normal volume of oil plus contaminants.
4. Have refrigerant filled by a pro. You can blow out a hose or compressor by filling with cans, and/or without the proper gauges and/or methodology.
5. Replenish the pulley driven fan clutch fluid - get it from Toyota - Thickest part number version is 08816-10001
6. Clean the condenser – looks like a front radiator. While you’re at it, clean the radiator.
7. Expansion valve(s) may need to be changed – especially after compressor failure. (Sorry, but I do not know how to diagnose bad expansion valves. I don’t know if you get a big gain from this when the originals were still good. Many people really like to replace these to do it right. If they are bad, the system will never work right. There are different types specific to different refrigerants.)
8. Old refrigerant hoses may leak. Many people really like to replace these to do it right. Some new compressors come with new hoses too.
9. Clean the front evaporator. This is accessed when the cockpit blower fan is removed. Leaves, bugs, hair, dirt, will accumulate here.
10. Install the 75C Radiator Fan Switch to engage the electric fan at lower temperatures.
FLUSH & FILL: To flush the system use professional equipment and/or: Disconnect hoses and remover dryer. Flush out the old components with a cleaning fluid, and proper equipment. (Do not use compressed air, since it puts moisture into the system, and can generate corrosive acid compounds. Incompatible oils or contaminants can ruin your compressor.) You should put oil into a new compressor, and turn it manually a few times before you turn on the A/C, and after flushing. Connect hoses, and vacuum out the system immediately after the flush. Do not expose the inlets of the new receiver/dryer and compressor to the atmosphere until you are ready to add oil and connect hoses.
ORIFICE TUBE: Replacement of the orifice tube and dryer are required for warranties on American compressors. There is no orifice tube on a 928. The dryer filters contaminants.
REFRIGERANTS:
If you have R12, stick with it, or for less expensive refills - Hot Shot or MP39 sound good as inexpensive, compatible refills. R134A conversion can reduce efficiency 8-12%.
MORE INFORMATION OR PARTS: The Big 3 can provide parts. I have found excellent prices and service at 928 Specialists (828) 766-9280. See the griffiths.com site for parts and info. See the link below for in depth discussions by people from whom I have derived some of my recommendations:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001183" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001183</a>
More vacuum and electrical troubleshooting:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=002171" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=002171</a>
VACUUM GREMLINS ARE…STRANGER THAN FICTION! There are 5 climate control actuators on an 86 model with flimsy rubber diaphragms to go bad. I have replaced 4 now. The remainder of this document addresses some of the vacuum actuators.
HEATER CONTROL VALVE: The A/C will never be cold with a defective heater control valve or vacuum leak at it’s adjoining actuator. The valve (under the air filter) will by default bleed hot water into the heater core unless all vacuum leaks on the dash side of the firewall (and engine compartment extension/heater control valve) are fixed. The valve can be defective even if vacuum is good. The valve can be installed 180degrees reversed. The white side of the valve goes toward the firewall side. (If you replace the valve, also replace the 3-inch long water hose connected to it.) See this link on Greg Nichol’s site for applicable vacuum testing procedures from Wally and company:
<a href="http://ourworld.compuserve.com/homepages/nichols/tip509.htm" target="_blank">http://ourworld.compuserve.com/homepages/nichols/tip509.htm</a>
RECIRCULATION FLAP ACTUATOR: On my car the vacuum test through the black test port line did not reveal this faulty actuator. You can feel the flap by putting your fingers through a 2-3 inch rectangular hole behind the glove box. You can easily push it up. If the flap does not rise up when the engine starts, with the A/C and Heater controls off, it probably has a leaking actuator. See Tony’s great pictorial write-up about the recirculation flap replacement.
<a href="http://members.rennlist.com/v1uhoh/air.htm" target="_blank">http://members.rennlist.com/v1uhoh/air.htm</a>
Tony’s Center Comb and Heater Valve Lock-downs: (Note: A properly working a/c system requires none of these, or any other non-original modifications.)
<a href="http://members.rennlist.com/v1uhoh/summer.htm" target="_blank">http://members.rennlist.com/v1uhoh/summer.htm</a>
Tony’s CENTER COMB ACTUATOR Replacement:
<a href="http://members.rennlist.com/v1uhoh/combflap.htm" target="_blank">http://members.rennlist.com/v1uhoh/combflap.htm</a>
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
<img src="graemlins/jumper.gif" border="0" alt="[jumper]" />
RULES:
1. If you open the system: Replace the dryer. Vacuum the moisture out.
2. If you convert to R134A, flush the old oil & contaminants out. Change o-rings. Oil o-rings before installation.
3. If o-rings are ever exposed, replace them with new ones.
RECOMMENDATIONS:
1. VACUUM GREMLINS ARE…STRANGER THAN FICTION! Fix them all before you try anything else.
2. With inexpensive R12 compatible refrigerants available, it may not be so good to convert to R134A. However, people have obtained very good results in 928s with R134A. See REFRIGERANTS below.
3. If you open the system, flush it too. By now it may have 2 or 3 times over the normal volume of oil plus contaminants.
4. Have refrigerant filled by a pro. You can blow out a hose or compressor by filling with cans, and/or without the proper gauges and/or methodology.
5. Replenish the pulley driven fan clutch fluid - get it from Toyota - Thickest part number version is 08816-10001
6. Clean the condenser – looks like a front radiator. While you’re at it, clean the radiator.
7. Expansion valve(s) may need to be changed – especially after compressor failure. (Sorry, but I do not know how to diagnose bad expansion valves. I don’t know if you get a big gain from this when the originals were still good. Many people really like to replace these to do it right. If they are bad, the system will never work right. There are different types specific to different refrigerants.)
8. Old refrigerant hoses may leak. Many people really like to replace these to do it right. Some new compressors come with new hoses too.
9. Clean the front evaporator. This is accessed when the cockpit blower fan is removed. Leaves, bugs, hair, dirt, will accumulate here.
10. Install the 75C Radiator Fan Switch to engage the electric fan at lower temperatures.
FLUSH & FILL: To flush the system use professional equipment and/or: Disconnect hoses and remover dryer. Flush out the old components with a cleaning fluid, and proper equipment. (Do not use compressed air, since it puts moisture into the system, and can generate corrosive acid compounds. Incompatible oils or contaminants can ruin your compressor.) You should put oil into a new compressor, and turn it manually a few times before you turn on the A/C, and after flushing. Connect hoses, and vacuum out the system immediately after the flush. Do not expose the inlets of the new receiver/dryer and compressor to the atmosphere until you are ready to add oil and connect hoses.
ORIFICE TUBE: Replacement of the orifice tube and dryer are required for warranties on American compressors. There is no orifice tube on a 928. The dryer filters contaminants.
REFRIGERANTS:
If you have R12, stick with it, or for less expensive refills - Hot Shot or MP39 sound good as inexpensive, compatible refills. R134A conversion can reduce efficiency 8-12%.
MORE INFORMATION OR PARTS: The Big 3 can provide parts. I have found excellent prices and service at 928 Specialists (828) 766-9280. See the griffiths.com site for parts and info. See the link below for in depth discussions by people from whom I have derived some of my recommendations:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001183" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001183</a>
More vacuum and electrical troubleshooting:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=002171" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=002171</a>
VACUUM GREMLINS ARE…STRANGER THAN FICTION! There are 5 climate control actuators on an 86 model with flimsy rubber diaphragms to go bad. I have replaced 4 now. The remainder of this document addresses some of the vacuum actuators.
HEATER CONTROL VALVE: The A/C will never be cold with a defective heater control valve or vacuum leak at it’s adjoining actuator. The valve (under the air filter) will by default bleed hot water into the heater core unless all vacuum leaks on the dash side of the firewall (and engine compartment extension/heater control valve) are fixed. The valve can be defective even if vacuum is good. The valve can be installed 180degrees reversed. The white side of the valve goes toward the firewall side. (If you replace the valve, also replace the 3-inch long water hose connected to it.) See this link on Greg Nichol’s site for applicable vacuum testing procedures from Wally and company:
<a href="http://ourworld.compuserve.com/homepages/nichols/tip509.htm" target="_blank">http://ourworld.compuserve.com/homepages/nichols/tip509.htm</a>
RECIRCULATION FLAP ACTUATOR: On my car the vacuum test through the black test port line did not reveal this faulty actuator. You can feel the flap by putting your fingers through a 2-3 inch rectangular hole behind the glove box. You can easily push it up. If the flap does not rise up when the engine starts, with the A/C and Heater controls off, it probably has a leaking actuator. See Tony’s great pictorial write-up about the recirculation flap replacement.
<a href="http://members.rennlist.com/v1uhoh/air.htm" target="_blank">http://members.rennlist.com/v1uhoh/air.htm</a>
Tony’s Center Comb and Heater Valve Lock-downs: (Note: A properly working a/c system requires none of these, or any other non-original modifications.)
<a href="http://members.rennlist.com/v1uhoh/summer.htm" target="_blank">http://members.rennlist.com/v1uhoh/summer.htm</a>
Tony’s CENTER COMB ACTUATOR Replacement:
<a href="http://members.rennlist.com/v1uhoh/combflap.htm" target="_blank">http://members.rennlist.com/v1uhoh/combflap.htm</a>
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
<img src="graemlins/jumper.gif" border="0" alt="[jumper]" />
Thread Starter
Rennlist Member
Rennlist Site Sponsor
Joined: Jun 2001
Posts: 6,469
Likes: 14
From: Ball Ground, GA
>Does anyone sell a complete kit of 0-ring >replacements for my '87S4 w/rear AC?
Yes. Call Jeannie at (828) 766-9280 for kits (either with or without rear air).
>My vacuum pump will only pull 20"hg. Is this >sufficient?
No. You need a MUCH better vacuum than that to remove moisture and non-condensibles.
Yes. Call Jeannie at (828) 766-9280 for kits (either with or without rear air).
>My vacuum pump will only pull 20"hg. Is this >sufficient?
No. You need a MUCH better vacuum than that to remove moisture and non-condensibles.
Advanced
Joined: Apr 2002
Posts: 64
Likes: 0
From: TX
I am having a/c cooling problems with my US 86.
It cools, but not really "cold".
Anyway, starting going through the vacuum line checks, and have good (20+in.Hg) back to the center console.
Here's where I get lost.
The green and blue vacuum lines hold great vacuum (25in.Hg) but the orange and yellow lines BOTH leak-down pretty quickly (from 5in.Hg to zero in a second)
In the desire to NOT take apart more than I need to, what are the orange and yellow vacuum lines hooked up to, and what do I need to remove to replace those bad acuators??
Thanks!!
Barry
It cools, but not really "cold".
Anyway, starting going through the vacuum line checks, and have good (20+in.Hg) back to the center console.
Here's where I get lost.
The green and blue vacuum lines hold great vacuum (25in.Hg) but the orange and yellow lines BOTH leak-down pretty quickly (from 5in.Hg to zero in a second)
In the desire to NOT take apart more than I need to, what are the orange and yellow vacuum lines hooked up to, and what do I need to remove to replace those bad acuators??
Thanks!!
Barry
Burning Brakes
Joined: Jul 2001
Posts: 1,051
Likes: 1
Hi Barry,
You have 2 bad actuators. See Greg Nichol’s tips for this data, and more instructions: <a href="http://www.nichols.nu/tips.htm" target="_blank">http://www.nichols.nu/tips.htm</a>
The lines are:
A - Yellow - Footwell Flap
B - Green - Defroster Flap
C - Orange - Center Nozzle Stage One
D - Brown - Center Nozzle Stage Two
E - Red - Mixing Flap and Heating Valve
F - Blue -Fresh Air Bypass Flap
Your year model is different, and orange is center comb. See Tony’s site for a replacement procedure: <a href="http://members.rennlist.com/v1uhoh/combflap.htm" target="_blank">http://members.rennlist.com/v1uhoh/combflap.htm</a>
It has been a few years since I did the footwell actuator. It was probably the one under the dash on the driver’s side. If so, I pulled the center console, and maybe the instrument pod to get to it. You need to confirm that before you do that. Dave Roberts at 928 Specialists can supply parts and proper advice. Nichol’s site has procedures for console and pod removal. It seems that the defroster actuator was in that area. I would do it at the same time.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
You have 2 bad actuators. See Greg Nichol’s tips for this data, and more instructions: <a href="http://www.nichols.nu/tips.htm" target="_blank">http://www.nichols.nu/tips.htm</a>
The lines are:
A - Yellow - Footwell Flap
B - Green - Defroster Flap
C - Orange - Center Nozzle Stage One
D - Brown - Center Nozzle Stage Two
E - Red - Mixing Flap and Heating Valve
F - Blue -Fresh Air Bypass Flap
Your year model is different, and orange is center comb. See Tony’s site for a replacement procedure: <a href="http://members.rennlist.com/v1uhoh/combflap.htm" target="_blank">http://members.rennlist.com/v1uhoh/combflap.htm</a>
It has been a few years since I did the footwell actuator. It was probably the one under the dash on the driver’s side. If so, I pulled the center console, and maybe the instrument pod to get to it. You need to confirm that before you do that. Dave Roberts at 928 Specialists can supply parts and proper advice. Nichol’s site has procedures for console and pod removal. It seems that the defroster actuator was in that area. I would do it at the same time.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />