No Heat,Compressor won't shut off
02-08-2018, 06:13 AM
#1
Rennlist Member
Thread Starter
No Heat,Compressor won't shut off
I/m posting this for a friend, 1991 C2 with 95,000 miles
no heat, compressor won't shut off
These are the responses he got from some people he reached out to. Was wondering if anyone has had the same problems, and has any advise/solutions?
thanks
four faults in system:
14: Evaporator temp sensor
23: Footwell flap motor
41: Condenser blower
44: Rear blower motor, speed 2
Climate control panel rebuilt by ECUDoctors.com for previous owner. I'm using the rennlist scantool for access. Rear blower motor temp sensor and resistor both replaced with oe parts.
Compressor runs irrespective of panel settings (presently unplugged). Cannot get any heat in car. Faults listed above. I'm not well versed in these cars and am no longer able to crawl around under dash. I'm looking for pointers for fixing this system.
~~~~~~~~~~~~~~~~~~~~~~~~
As I recall, the blend door motors are in the front trunk area in the cowl. There are a bunch of them. I would confirm that they are all working full swing. It may be possible that the temp door is stuck or the motor is bad. Good luck.
Richard Zaagman
Owner/Manager
Community Automotive Repair Inc.
Grand Rapids, Michigan, USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I can't answer your question. You can use this website to troubleshoot the system.
https://www.bergvillfx.com/porschehvac1
These issues are time consuming and can be spendy, so get an okay for the repair that allows you to do a proper job, or walk away!
Obie Bradshaw
Technician
European AutoHaus
Spokane, Washington, USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check the left and right heat control boxes under vehicle
William Ignich
Owner
Birmingham Imports Service Center, Inc.
Royal Oak, Michigan, USA
~~~~~~~~~~~~~~~~~~~~~~~~
Yes, check for the boxes under the car and also behind both kick panels in the passenger compartment there are blower motors and flaps. If those blower motors fail, no air will be brought into the passenger compartment. The flaps need to be opened by air movement.
Frank Hanrahan
Owner/Technician
Haus of Performance
Costa Mesa, California, USA
no heat, compressor won't shut off
These are the responses he got from some people he reached out to. Was wondering if anyone has had the same problems, and has any advise/solutions?
thanks
four faults in system:
14: Evaporator temp sensor
23: Footwell flap motor
41: Condenser blower
44: Rear blower motor, speed 2
Climate control panel rebuilt by ECUDoctors.com for previous owner. I'm using the rennlist scantool for access. Rear blower motor temp sensor and resistor both replaced with oe parts.
Compressor runs irrespective of panel settings (presently unplugged). Cannot get any heat in car. Faults listed above. I'm not well versed in these cars and am no longer able to crawl around under dash. I'm looking for pointers for fixing this system.
~~~~~~~~~~~~~~~~~~~~~~~~
As I recall, the blend door motors are in the front trunk area in the cowl. There are a bunch of them. I would confirm that they are all working full swing. It may be possible that the temp door is stuck or the motor is bad. Good luck.
Richard Zaagman
Owner/Manager
Community Automotive Repair Inc.
Grand Rapids, Michigan, USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I can't answer your question. You can use this website to troubleshoot the system.
https://www.bergvillfx.com/porschehvac1
These issues are time consuming and can be spendy, so get an okay for the repair that allows you to do a proper job, or walk away!
Obie Bradshaw
Technician
European AutoHaus
Spokane, Washington, USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check the left and right heat control boxes under vehicle
William Ignich
Owner
Birmingham Imports Service Center, Inc.
Royal Oak, Michigan, USA
~~~~~~~~~~~~~~~~~~~~~~~~
Yes, check for the boxes under the car and also behind both kick panels in the passenger compartment there are blower motors and flaps. If those blower motors fail, no air will be brought into the passenger compartment. The flaps need to be opened by air movement.
Frank Hanrahan
Owner/Technician
Haus of Performance
Costa Mesa, California, USA
02-09-2018, 07:57 AM
#3
Rennlist Member
The list of CCU faults pretty much tells you what the problems are:
A failed evaporator sensor will make the CCU unable to check evap temperature, and thus no shutoff of the compressor. I would advise to not use A/C before this is fixed, there is risk of evaporator freezing and damage. Changing the evaporator radiator core is an expensive job, but changing the sensor is done in minutes. Be careful to position it correctly to get proper contact with the evap radiator.
The condenser blower needs fixing, I would guess the fan motor low speed resistor is damaged. This is a common fault, and will cause high pressure in the A/C system, which is undesirable. See this page for details.
The rear blower operation must be checked. I would guess there's a problem with the fan motor relay since it is not running on full speed. A failing rear fan will be detected by the CCU as a fault, and the two main blowers in the front will shut down automatically. This is probably why there's no heated air available.
By the way, your friend might reconsider his consultants. There is no need to check the heat dump valves under the car. "Haus of Performance" representative is also wrong, there are no fans or heat regulating elements behind the 964 kickpanels/foot well carpet walls.
A full check of the five HVAC servo motors is done in minutes. However, it seems to not be necessary, there are no fault codes stored on their operation.
Regarding the cost/time on this: I would estimate half an hour of work for diagnosing all the above issues. Changing the condenser fan low resistor and 2-3 hours, (consider changing the oil cooler fan resistor while the bumper is off) and changing the evap sensor/rear fan relay is 1/2h. Totals to half a day at a workshop.
Cheers,
Tore
A failed evaporator sensor will make the CCU unable to check evap temperature, and thus no shutoff of the compressor. I would advise to not use A/C before this is fixed, there is risk of evaporator freezing and damage. Changing the evaporator radiator core is an expensive job, but changing the sensor is done in minutes. Be careful to position it correctly to get proper contact with the evap radiator.
The condenser blower needs fixing, I would guess the fan motor low speed resistor is damaged. This is a common fault, and will cause high pressure in the A/C system, which is undesirable. See this page for details.
The rear blower operation must be checked. I would guess there's a problem with the fan motor relay since it is not running on full speed. A failing rear fan will be detected by the CCU as a fault, and the two main blowers in the front will shut down automatically. This is probably why there's no heated air available.
By the way, your friend might reconsider his consultants. There is no need to check the heat dump valves under the car. "Haus of Performance" representative is also wrong, there are no fans or heat regulating elements behind the 964 kickpanels/foot well carpet walls.
A full check of the five HVAC servo motors is done in minutes. However, it seems to not be necessary, there are no fault codes stored on their operation.
Regarding the cost/time on this: I would estimate half an hour of work for diagnosing all the above issues. Changing the condenser fan low resistor and 2-3 hours, (consider changing the oil cooler fan resistor while the bumper is off) and changing the evap sensor/rear fan relay is 1/2h. Totals to half a day at a workshop.
Cheers,
Tore