2004 Grand Prix HVAC control panel not working

[Lishap]

Hey guys looking for some help. 2004 Grand prix. HVAC panel stopped working once it started to get cold( 20-40 degrees out). It's the entire panel (Both heated seats, defroster and AC lights don't come on) i checked the fuses in the side fuse panel it was fine replaced it and the system reset or whatever it was and the panel worked again. Next morning same problem, removed the fuse and replaced and worked again. Then it threw a P0128 Code (coolant temp below regulated temp), cleared the code and replaced the thermostat and it hasn't come back and the car was working fine. Then the Car wasn't driven for about a week and next time it was driven the panel stopped working, tried the fuse removal and it didn't work this time. I don't think its the blend door actuator or the blower motor 1) bc its the entire panel not just the heat and fans, the entire panel, lights and all doesnt work 2) after being reset a couple of times it all came back with no issues all fan speeds and buttons were back.

Sorry for the long post but trying to give as much details about it as possible and trying to get this fixed ASAP as winter is on its way in. Thanks.

 

[Gregorius]

You have to have a bad ground/ bad ground wire going to the HVAC control module/panel under the dash somewhere. It's the only thing that would explain losing the heated seats <data bus> and the illumination for the HVAC as well as dead controls also.

G202 = right side upper left footwell

 

[Lishap]

Thanks, ill check into that. any specific i should be looking for other then a broken wire or anything?

 

[wstefan20]

Not sure if it'll help in your case but Google 2004 pontiac grand prix entertainment schematic autozone. Create a free account and there's 99% of wiring diagrams for our vehicles free