2005 Z71 Tahoe hot air

[Jasonrebellion]

I’ve owned it for about 2.5 years, had no issues with the AC, would freeze you out. I bought a new daily driver and I let it sit long enough to completely kill the battery to where it wouldn’t hold a charge. I replaced it with another yellow top Optima and it immediately started blowing the hottest air I’ve ever felt. Doesn’t matter what I set the temp on, just pure unadulterated heat out of both sides. I feel like it’s unlikely it just randomly sprung a leak from sitting for 2 months but I don’t know where to start and funds are limited. I have checked all the fuses. Thanks for any help. I did search before posting but may have missed something.

 

[mountie]

I just had my alternator replaced. Before it was replaced, at the repair shop, the A/C was perfect. Vents were cold. When I started the 2005 Yukon at the shop, with the new alternator, the vents were HOT.

I shut of the truck and restarted it ...... The vents went back to cold again, and perfect since.

( I think the vent actuators just needed some encouragement when I restarted. ? )

Do you have the rear A/C ? If so, is it hot?

 

[Scottydoggs]

 

[Fless]

There is also an updated calibration for many of the NBS HVAC controllers. @SnowDrifter had his updated recently IIRC.

Not sure if you have the manual or AUTO HVAC control.

 

[Jasonrebellion]

There is also an updated calibration for many of the NBS HVAC controllers. @SnowDrifter had his updated recently IIRC.

Not sure if you have the manual or AUTO HVAC control.

I have the auto

 

[Jasonrebellion]

I just had my alternator replaced. Before it was replaced, at the repair shop, the A/C was perfect. Vents were cold. When I started the 2005 Yukon at the shop, with the new alternator, the vents were HOT.

I shut of the truck and restarted it ...... The vents went back to cold again, and perfect since.

( I think the vent actuators just needed some encouragement when I restarted. ? )

Do you have the rear A/C ? If so, is it hot?

The rear ac has always been stuck on ac, but now it’s just blowing ambient air. The air out the front is pure heat though

 

[Fless]

On my '04 there are updated calibrations for both the front AUTO and rear HVAC controls.

 

[OR VietVet]

On my '04 there are updated calibrations for both the front AUTO and rear HVAC controls.

Can you post those steps.

 

[Fless]

Can you post those steps.

Calibrations are done with a scanner; a Tech 2 and TIS2000, or a capable bidirectional scanner with the GM online programming.

 

[ivin74]

I’ve owned it for about 2.5 years, had no issues with the AC, would freeze you out. I bought a new daily driver and I let it sit long enough to completely kill the battery to where it wouldn’t hold a charge. I replaced it with another yellow top Optima and it immediately started blowing the hottest air I’ve ever felt. Doesn’t matter what I set the temp on, just pure unadulterated heat out of both sides. I feel like it’s unlikely it just randomly sprung a leak from sitting for 2 months but I don’t know where to start and funds are limited. I have checked all the fuses. Thanks for any help. I did search before posting but may have missed something.

Do you know if the HVAC system has refrigerant?

 

[ScottyBoy]

My truck sat for almost a year while I waited on a new engine. After I FINALLY got a new crate engine installed, my AC was blowing HOT. Sure enough, I had no refrigerant. My Schrader valves had a small leak, and it sat long enough to leak out.
So check all the easy stuff first, make SURE that it still has refrigerant, then go from there.

 

[willinnashville]

Similar thing happened to me last week in my 2005 Denali. I disconnected the battery for a valve cover replacement. After I was finished I fired up and had hot air on the passenger side but cold air from the driver side. I did the recalibration steps basically the same as the video below and it's been fine ever since.

 

[willinnashville]