Help needed w/ Climate Control Module
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Rennlist Member
Joined: May 2007
Posts: 1,597
Likes: 188
From: Beaver Creek, CO
Help needed w/ Climate Control Module
'02 C4 cab w/ 57k mi on the clock - today the CCM stopped functioning properly. Compressor comes on, A/C is working but won't blow thru vents.
Getting erratic behavior as follows: Defroster is activated which is blowing cold air to the windshield. When I attempt to deactivate the defroster, each time I hit the button the fan speed drops down a notch. When I try depressing the Auto button, Temp up or down, or Fan speed up or down, nothing happens. Sometimes when I hit the Defroster button the Recirculating icon comes on - but the Recirc button won't turn it off...
I tried turning the car on/off several times and the erratic behavior continues. It completely shut down one time and would not activate until cycling power to the car again.
No CEL or other warning lights coming on. Any idea what's going on? I'd sure appreciate some help as the summer heat has returned to Colorado. Thanks in advance!
Getting erratic behavior as follows: Defroster is activated which is blowing cold air to the windshield. When I attempt to deactivate the defroster, each time I hit the button the fan speed drops down a notch. When I try depressing the Auto button, Temp up or down, or Fan speed up or down, nothing happens. Sometimes when I hit the Defroster button the Recirculating icon comes on - but the Recirc button won't turn it off...
I tried turning the car on/off several times and the erratic behavior continues. It completely shut down one time and would not activate until cycling power to the car again.
No CEL or other warning lights coming on. Any idea what's going on? I'd sure appreciate some help as the summer heat has returned to Colorado. Thanks in advance!
Thread Starter
Rennlist Member
Joined: May 2007
Posts: 1,597
Likes: 188
From: Beaver Creek, CO
Update - after sitting for 3 hours during meetings, upon startup the system started working as normal and performed well during the 1-hr drive home. All appears to be well and hopefully no future recurrence.
Drifting
Joined: Sep 2001
Posts: 2,467
Likes: 16
From: redmond wa
Not sure of your statement, question(?) overall, but....
Make sure the front radiator fans are both capable of running FULL TILT if and when needed. The system will AUTOMATICALLY switch off A/C functionality if the engine ECU detects (computes?) that the engine coolant level is rising (to)rapidly and might soon reach overheating.
This is considered normal operation for a car that is expected to be driven so hard at times that the additional A/C condenser heating load to the engine coolant radiators must be sacificed. No error codes result.
If you see it happen again the you can increase the cooling efficiency of the A/C quite dramatically via using the maximum cooling mode of the system. Changing the setpoint to maximum cooling results in bypassing the reheat/remix aspect of the system and thereby a much lighter load on the A/C compressor.
Then use the blower speed to adjust the system outflow cooling to your comfort zone.
'02 C4 cab w/ 57k mi on the clock - today the CCM stopped functioning properly. Compressor comes on, A/C is working but won't blow thru vents.
Getting erratic behavior as follows:
Defroster is activated which is blowing cold air to the windshield.
SOP...once the cabin atmospheric temperature reaches your setpoint, or closely nearby, the system will open ALL three airflow outlet paths, footwell, dash, AND defroster. The purpose of this is to more widely disperse the system's COOL & DRY airflow so as to not unduly discomfort those in the front seats.
There are 2 shortcomings to the approach...
1.) Loss of system cooling efficient due to high loss factor of the windshield glass.
2.) In a hot and humid climate the resulting formation of condensation on the windshield can prove to be hazardous if not quickly detected.
When I attempt to deactivate the defroster, each time I hit the button the fan speed drops down a notch.
Yes, but the temperature of the system outflow is adjusted to be lower in temperature. The effect of your closing off the deforster airflow path would be to reduce the air volume/te being used to maintain the cabin atmosphere at/near your setpoint. The system makes adustments to compensate...again, to prevent discomfort..
When I try depressing the Auto button, Temp up or down, or Fan speed up or down, nothing happens.
Hmmm...a problem..
Sometimes when I hit the Defroster button the Recirculating icon comes on - but the Recirc button won't turn it off...
My guess is that this is the inverse of wintertime system operation. During heating use the system WILL NOT allow extended use of RECIRCULATE absent the A/C being enabled. If it is cold enough even the activation of the A/C will not enable the sustained the use of recirculate.
This is to prevent build-up of cabin Rh, mostly due to human metabolism, and the resulting danger of windshield fogging.
If you should activate the defrost(defog/demist) mode in warm weather the quickest way to dehumidify the cabin atmosphere will be to use recirculate mode thereby raising the dehumidification effectiveness of the A/C. NO incoming HIGH Rh airflow.
I tried turning the car on/off several times and the erratic behavior continues. It completely shut down one time and would not activate until cycling power to the car again.
No CEL or other warning lights coming on. Any idea what's going on? I'd sure appreciate some help as the summer heat has returned to Colorado. Thanks in advance!
Getting erratic behavior as follows:
Defroster is activated which is blowing cold air to the windshield.
SOP...once the cabin atmospheric temperature reaches your setpoint, or closely nearby, the system will open ALL three airflow outlet paths, footwell, dash, AND defroster. The purpose of this is to more widely disperse the system's COOL & DRY airflow so as to not unduly discomfort those in the front seats.
There are 2 shortcomings to the approach...
1.) Loss of system cooling efficient due to high loss factor of the windshield glass.
2.) In a hot and humid climate the resulting formation of condensation on the windshield can prove to be hazardous if not quickly detected.
When I attempt to deactivate the defroster, each time I hit the button the fan speed drops down a notch.
Yes, but the temperature of the system outflow is adjusted to be lower in temperature. The effect of your closing off the deforster airflow path would be to reduce the air volume/te being used to maintain the cabin atmosphere at/near your setpoint. The system makes adustments to compensate...again, to prevent discomfort..
When I try depressing the Auto button, Temp up or down, or Fan speed up or down, nothing happens.
Hmmm...a problem..
Sometimes when I hit the Defroster button the Recirculating icon comes on - but the Recirc button won't turn it off...
My guess is that this is the inverse of wintertime system operation. During heating use the system WILL NOT allow extended use of RECIRCULATE absent the A/C being enabled. If it is cold enough even the activation of the A/C will not enable the sustained the use of recirculate.
This is to prevent build-up of cabin Rh, mostly due to human metabolism, and the resulting danger of windshield fogging.
If you should activate the defrost(defog/demist) mode in warm weather the quickest way to dehumidify the cabin atmosphere will be to use recirculate mode thereby raising the dehumidification effectiveness of the A/C. NO incoming HIGH Rh airflow.
I tried turning the car on/off several times and the erratic behavior continues. It completely shut down one time and would not activate until cycling power to the car again.
No CEL or other warning lights coming on. Any idea what's going on? I'd sure appreciate some help as the summer heat has returned to Colorado. Thanks in advance!
This is considered normal operation for a car that is expected to be driven so hard at times that the additional A/C condenser heating load to the engine coolant radiators must be sacificed. No error codes result.
If you see it happen again the you can increase the cooling efficiency of the A/C quite dramatically via using the maximum cooling mode of the system. Changing the setpoint to maximum cooling results in bypassing the reheat/remix aspect of the system and thereby a much lighter load on the A/C compressor.
Then use the blower speed to adjust the system outflow cooling to your comfort zone.
Racer
Joined: Dec 2011
Posts: 352
Likes: 13
Thread Starter
Rennlist Member
Joined: May 2007
Posts: 1,597
Likes: 188
From: Beaver Creek, CO
My climate control problems persist and none of the typical adjustments work:
Can't go into AUTO mode
Can't turn off compressor
Can't adjust temp up or down
Can't adjust fan speed up or down
It's either all "OFF" in manuell mode, or the system is all "ON" w/ compressor, defroster, full fans and temp locked at 72 deg. The only way to switch is by pressing the recirculation switch - all other switches are inoperable.
I hooked up a code reader, but no codes are present.
Could it be true that I have a bad ignition switch as mentioned by b8_rdc? I'd gladly pay the $9 to fix this issue before the snow flies...thanks for any help w/ this annoyance.
Can't go into AUTO mode
Can't turn off compressor
Can't adjust temp up or down
Can't adjust fan speed up or down
It's either all "OFF" in manuell mode, or the system is all "ON" w/ compressor, defroster, full fans and temp locked at 72 deg. The only way to switch is by pressing the recirculation switch - all other switches are inoperable.
I hooked up a code reader, but no codes are present.
Could it be true that I have a bad ignition switch as mentioned by b8_rdc? I'd gladly pay the $9 to fix this issue before the snow flies...thanks for any help w/ this annoyance.
Last edited by skiracer; Sep 24, 2013 at 04:53 PM. Reason: mis -typed
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Thread Starter
Rennlist Member
Joined: May 2007
Posts: 1,597
Likes: 188
From: Beaver Creek, CO
I've replaced the headlight switch and managed that task - is the ignition switch a more challenging project? I don't tend to wrench on my own cars, but I've been able to do a fair amount on the Pcar thus far.
Intermediate
Joined: May 2013
Posts: 29
Likes: 1
Try pulling the module out, removing the connector, and cleaning the contacts. Reassemble with dielectric grease. I've cured some weird behavior in both the climate control and the instrument cluster after doing this.
Thread Starter
Rennlist Member
Joined: May 2007
Posts: 1,597
Likes: 188
From: Beaver Creek, CO
Rennlist Member
Joined: Jul 2012
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From: US
From the variety of symptoms and flakiness of behavior, it does sound like it's the climate control computer itself.
Removing/refitting the connectors and using some electronic contact cleaner and/or dielectric grease can't hurt, though use the grease very sparingly. It might be short lived fix even if it helps... More likely you have a failing component inside the module or a bad trace somewhere, and heating/cooling and current cycles cause it to behave erratically.
I think the modules are pricey, but there are always used ones on eBay.
The displays on those modules fail frequently, they still work but segments go bad on the display. Maybe somebody has a working module with a damaged display that you could borrow to swap in for troubleshooting?
Also, not sure how much help it will be, but here's the schematic for the HVAC control systems... (click for full res)
Removing/refitting the connectors and using some electronic contact cleaner and/or dielectric grease can't hurt, though use the grease very sparingly. It might be short lived fix even if it helps... More likely you have a failing component inside the module or a bad trace somewhere, and heating/cooling and current cycles cause it to behave erratically.
I think the modules are pricey, but there are always used ones on eBay.
The displays on those modules fail frequently, they still work but segments go bad on the display. Maybe somebody has a working module with a damaged display that you could borrow to swap in for troubleshooting?
Also, not sure how much help it will be, but here's the schematic for the HVAC control systems... (click for full res)
Three Wheelin'
Joined: Apr 2010
Posts: 1,708
Likes: 78
From: Delaware, USA
A bit off-topic, but there are several types of display repair kits for these climate control displays. One even is a perfect match for the OEM display.
Doesn't sound like that's the OP's problem, though.
Doesn't sound like that's the OP's problem, though.
