barry1022

I have an '05 Z71 and the A/C can be working fine and then all of the sudden, it starts blowing hot air. If I turn the truck off and restart it, the A/C goes back to working like normal until it happens again.

This is an ongoing thing, I hope someone can give me some advice. Thanks in advance.

evans906

The system works fine for 10 minutes. Then it starts blowing warm air. If you shut it off for 10 minutes and turn it back on it blows cold air for 10 minutes. And the process repeats itself again. You have moisture in the system. The moisture is freezing and blocking the orifice tube or the evaporator. The a/c system was opened to replace something and the system was never evacuated or you have a leak. Moisture reacts with refrigerant to form hydrochloric acid which damages the systems internal components.

barry1022

Thanks for the help, I will get it checked out. I didn't buy it new so I don't know for sure if the AC system was ever opened or if I have a leak.

Thanks again.

barry1022

evans906......the explaination you gave for my problem almost seems like it should be happening all the time. Instead, it only happens intermittenly and if I pull off the road and turn the truck off then back on, it goes back to working normally.

Would you think there is some kind of sensor thats not working correctly? If not, I'll have to take it and have it checked for leaks and moisture.

Thanks again....

evans906

If the compressor clutch is engaging it's not the high or low pressure cut out switch. There is a cycling clutch switch. It cycles the compressor clutch on and off to maintain evaporator temperatures above freezing. But moisture in the system is what's freezing. As soon as you turn off the compressor the pressures in the system begin to equalize. The evaporator pressure increases and warms up. That warms the sensing bulb on the cycling clutch switch enough to let the switch close. then you turn on the a/c the compressor clutch engages and the cycle begins again. Take the vehicle to a shop and tell them what's going on, I have to bet it's moisture in the system. Please let me know what you find out. I've been known to be wrong. Thank You.

Mike115

I'm having exactly the same problem as barry1022. However, mine started on the passenger side of the dual a/c and has now moved to the driver side. I think the moisture would affect both sides. When the driver side goes hot the passenger side is cold. Shut the engine off and it immediately blows cold again. Please help!!

Mike115

Barry1022,
I've driven for two days with the drivers side vent closed using only the vents in the center and the passenger vents and have not had a problem. I'm wondering if the extra back pressure on the doors is helping?

tahoe101

Does it have an electric fan for cooling or clutch type?

Dixieman24

My avalanche did the same thing on driver side. With air on, the driver side would start blowing heat and it occurred more the longer I put off fixing it. You could turn the truck off and back on and it would work fine for a few minutes and then do it again. Turns out there are four actuators under dash that commonly cause problems like this. The actuators are for 1. Driver temperature 2. Passenger temperature. 3. Fresh air/ recirculating vent. 4. Mode(floor, vents, defrost). I replaced the driver temperature actuator which was pretty simple to do fixing my problem. The actuators are pretty expensive, I think I paid like $150 for it. It's located under dash on passenger side.