AC blows hot sometimes

I have a 2004 Chevy Avalanche with a strange AC problem. Normally my AC works just fine but about once a week or so it will suddenly blow heat instead of AC and there is nothing I can do to the AC controls to stop it. The only fix I have found that works is to completely shut the car off and start it again. By doing so the AC returns to normal and blows cold again. Any idea what is happening here?

Thanks.

 

Your a little low on the necessary refrigerant
It's not a real DIY safe procedure, might want to bring it in to an A/C pro

 

Pressure was checked (by amatuers) and found to be slightly high (in red zone). This is an indication that it has enough charge? Also - I have a strange occurance in which heat will come out on one side of vehicle and AC on the other side - this vehicle is equiped with dual controls for left and right side but both are set at max cool when this happens. Restarting car brings it back to normal.

THX.

 

Ahhh...if that's accurate then it could be a different problem
The right air is not going the right place, or the compressor is clicking off
I'm not familiar with the Avalanche
Could be a vacuum or computer/electrical problem

 

i have the same problem with my 04 avalanche, have you figured out whats the problem?

 

No I haven't figured it out. I am wondering if this vehicle has a cab filter and if that could have anything to do with it. I am also using the recirculation button to see if it makes a difference and so far it hasn't reoccurred. I can tell you that it will correct itself by turning the engine off and restarting. Strange that this seems to be isolated to 04 avalanches.

 

Nope - common problem. This is caused by the low pressure AC cycling switch going bad. It's easy to replace yourself. It plugs into the silver canister near the firewall, on the passenger side. Costs about $20. There's a GM TSB on this. While the bulletin says it only applies to up to 2003, I've hard of newer vehicles also having the problem. Tell your dealer to look this up.

Bulletin No.: 03-01-39-007

Date: May 29, 2003

TECHNICAL

Subject:
Air Conditioning (A/C) Inoperative/Intermittent, A/C Blows Warm Air (Replace A/C Low Pressure Cycling Switch)

Models:
2003 Cadillac Escalade, Escalade EXT, Escalade ESV
2002-2003 Chevrolet TrailBlazer, TrailBlazer EXT
2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2002-2003 GMC Envoy, Envoy XL
2003 GMC Sierra, Yukon, Yukon XL
2002-2003 Oldsmobile Bravada
2003 HUMMER H2

Condition

Some customers may comment that the A/C system is intermittently inoperative or blows warm air.

Cause

An intermittent inoperative (open) A/C low pressure cycling switch may be the cause. This is an intermittent condition and temperatures may play a critical role if the vehicle is in the failed mode or operating as designed.

I left out procedures but basically, you need to replace the cycling switch, which is listed below with the updated part #. Good Luck.


89040362- Switch, Pressure Cycling.

 

Thanks for info. I'll see dealer with your bulletin. Still skeptical though because it just doesn't make sense that cold AC would blow out passenger side and hot heat out driver side due to a cycling switch that should control both sides? right?

 

You're probably right. I didn't catch that, in your second post, about hot on one side, and cold on the other. Interesting for sure.

 

ok if it is blowing warm one side and it auto temp ur going to find the actuator for the right air mix door losing position
i have seen a few of them the actuator is on the top of the hvac case and u need the dash off to replace it

 

Dashboard maybe required, but may not as well. A Dodge dealership said I had to remove the entire dashboard and purge AC system to replace the blend door actuator on my wifes Stratus, they wanted $800.

Turns out I could just reach up under the dash after just removing the center console and replace without ripping everything apart.

 

lol this one has to come off they mounted right on top and then ran a duct over it service info actually says to remove whole dash but if u pull the top pad and pry up on the duct u can barely sneak it out i have the pleasure of one coming in under warranty on friday to do pay for it really sucks

 

I just paid $1500 to rebuild transmission at 123K miles and 3.5 years old - now this. Time to trade I think.

 

I have to ask - are they not honoring any of this under warranty or have you surpassed it already?