Rear HVAC Problem.

[mqayyum]

Hi everybody,

I owned 2003 GMC Envoy XL SLT since 2011. since I bought this car, my rear AC was not working at all.

Just recently before the real summer starts, I plan to get it repaired. My electrician advised me to replace AC-15-72813 A/C Blower Motor Switch/Resistor but after replacing it still the blower is not working. after a thorough check they said either the Fan Knob or rear Climate Control Assembly is faulty.

I tried myself to figure it out and see even i put the Fan Knob on 'R' there is no display on rear Climate Control Assembly. I tried to look for one in the market but it is not available or the model that is available is different with 16 pin connector while i have with 32 pin connector.

Is there anybody who can help me to solve this issue. I appreciate your quick response.

Best regards, Qayyum

 

[The_Roadie]

There's about 20 of them on Ebay right now, as low as $35. Just search for "trailblazer rear climate control".

But when you say the AC doesn't work, you really mean the rear BLOWER doesn't run?

If you get no display on the rear control module, are you sure it isn't a simple power/fuse problem? Do you have a meter and a bit of electrical troubleshooting experience?

There is also an in-line fuse in the rear wiring near the module you just replaced. Did you check the module connector to make sure you had 12V there?

 

[mqayyum]

Hi roadie
Thanks for your quick response. I will search again on ebay but i see it difficult to deliver these items to Saudi Arabia (Middle East).

Yes it is a rear BLOWER that does not work. I have checked the 30A fuse that is installed on the blower part. It has power and fuse is also not blown. I also tried to directly give power and ground to blower and it works fine but through control not at all.

I appreciate if you give me to check power on the rear control module. If possible can I get pinout detail of this module connector. Anyway as far as power is concern to this module I can see the light is on (I mean the two bulbs inside has power) but I am not sure if this is enough.May be there are other pins that provide power the the control module.

 

[The_Roadie]

In general, the lamps inside modules and switches are fed by the dimmable lamp busses coming from the BCM (there are two, one for LEDs and one for incandescent). Module power always comes from different wiring, usually orange.

View attachment 28472

 

[mqayyum]

Dear Roadie,

The problem is solved. Today I purchased used Control Module from Junkyard and it is working fine.

Thanks a lot for all your support.

Just one question? When I operate rear AC first time it takes about 30 to 40 second to start blower on whatever speed I select 1 2 or 3. Is it normal or require some settings.

Once again... Thank you very much.

Qayyum

 

[dazingla]

Dear Roadie,

The problem is solved. Today I purchased used Control Module from Junkyard and it is working fine.

Thanks a lot for all your support.

Just one question? When I operate rear AC first time it takes about 30 to 40 second to start blower on whatever speed I select 1 2 or 3. Is it normal or require some settings.

Once again... Thank you very much.

Qayyum

Mine also does but usually like 15 seconds. dunno why but everything does work fine afterwards