2002 Envoy rear air problems

xforbiddenone

Original poster
Member
Jun 5, 2012
4
Well guys, I have a 2002 Envoy XL sitting around with two problems that just might be connected to each other.

Like many users here, I was having trouble with the rear HVAC actuators, the top vents don't work, and on a side note, on the center console where passengers can change hot or cold, fan speed and leg or head vents, The vent control will not move off of showing arrows pointing to head and feet.

Now, I've replaced both actuators in the back, and I'm still having the same problem. Did I end up with a bad actuator replacement, or does the center control have something to do with this? Switching from hot to cold appears to be working fine. And as mentioned, fan control works fine. I just cannot get air to come out of the top vents without manually changing the air flow.

I'm also concerned about the middle console not changing off it's little icon.

Where do I go from here, and what can I do about it? ( and yes, both problems were present BEFORE taking it apart )
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The middle console control module might be dead. I'd look for a local buddy to swap with to experiment.

When you swapped the actuators, did you disconnect the battery or pull the fuse to force a recalibration? And did you follow the recalibration process of not touching any controls for 90 seconds after turning the ignition on for the first time after?
 

xforbiddenone

Original poster
Member
Jun 5, 2012
4
the roadie said:
The middle console control module might be dead. I'd look for a local buddy to swap with to experiment.

When you swapped the actuators, did you disconnect the battery or pull the fuse to force a recalibration? And did you follow the recalibration process of not touching any controls for 90 seconds after turning the ignition on for the first time after?



I should have been more detailed, my apologies. Yes, I disconnected the battery for around 10 minutes, then afterwards I turned the ignition on ( without starting it of course ) waited about two minutes like that and then started the truck to test if the actuators work.

The thing that gets me is the center console's fan speed and heat adjustments work, just not the changing of the vent's air flow... I'll take a picture of it sometime tomorrow if it still sounds confusing.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Do you have a meter and want to get into the signals from the control module to the rear airflow actuator? One way to be sure.

Does the module just ignore any presses on the airflow mode button? Could it be just a sticky/oxidized button on the module? You should be able to disassemble it and look/clean it.
 

xforbiddenone

Original poster
Member
Jun 5, 2012
4
the roadie said:
Do you have a meter and want to get into the signals from the control module to the rear airflow actuator? One way to be sure.

Does the module just ignore any presses on the airflow mode button? Could it be just a sticky/oxidized button on the module? You should be able to disassemble it and look/clean it.

It's possible the module could just be sticky or something caused it to become loose, But yes, it just ignores any presses on it, it seems to be a little stiff pushing in but it does push in. Is there a guide on how to disassemble that area to check the button?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I seem to remember the module can be pried out from the front with no screws. THen typically the rear cover comes off the module with some easy to break plastic clips. Then you get to the PCB inside. You have to adapt your entry strategy as you get deeper, is my experience working with the evil module designs. I'd guess somebody spilled soda in it.
 

neelskit

Member
Dec 7, 2011
69
Can you get the vent mode to change from the front controls? On my EXT, the rear system mimics what the front mode and front passenger temp is set to when the front fan speed (by the shifter) is set to 1, 2, or 3. If not, I would lean towards a bad rear control head. If you are able to change the vent mode with the front controls, then you might be on the right track with a stuck button.
 

xforbiddenone

Original poster
Member
Jun 5, 2012
4
neelskit said:
Can you get the vent mode to change from the front controls? On my EXT, the rear system mimics what the front mode and front passenger temp is set to when the front fan speed (by the shifter) is set to 1, 2, or 3. If not, I would lean towards a bad rear control head. If you are able to change the vent mode with the front controls, then you might be on the right track with a stuck button.

Sorry for the delay, with the hot weather I haven't been working to much into this, I just recently tried to use the front control to affect the back, and still have nothing with it. Would a bad control head be able to cause all of this is my real question, Really running low on options it seems haha
 

neelskit

Member
Dec 7, 2011
69
xforbiddenone said:
Sorry for the delay, with the hot weather I haven't been working to much into this, I just recently tried to use the front control to affect the back, and still have nothing with it. Would a bad control head be able to cause all of this is my real question, Really running low on options it seems haha

Assuming the actuator and wiring are good, I would suspect a bad control head. You should be able to get a used one off ebay reasonably. Make sure the replacement you get is for an XL/EXT. The SWB control head looks very similar.
 

Forum Statistics

Threads
23,778
Posts
643,209
Members
19,410
Latest member
Veteranservingyou