Ac Problem With 2004 Suburban - Very Odd

[greywolf2112]

I have a 2004 Suburban, 8.1L engine, LT model that is loaded. Has the automatic climate control, etc.

 

Lately, it has started having an issue with the AC. I'll start the vehicle, and like it has always done it will wait about 2-3 minutes before the AC kicks on (this is normal). It will quickly ramp up to whatever fan speed it needs, and then run sometimes for 5-15 minutes (sometimes longer), nice and cold. Then, suddenly, its like someone switched it over to the HOTTEST heater setting there is. Nothing but blistering hot air coming out the vents.

 

Turning it off and then on again doesn't change it back. Kicking the auto temp higher or lower doesn't help. Turning it over to HEAT and then back, turning off the AUTO, none of it works. After I've parked it for a few hours, it goes back to operating normally again (for 5-15 minutes) and then starts the problem all over again.

 

Bad relay switch? Computer? Freon about gone? I'm at a loss here. Obviously need to take it in to the mechanic, but afraid of the possibilities. Vehicle only has about 60,000 miles on it.

[greywolf2112]

Hmm, seems I have you guys stumped!

[Zembonez]

If it gets cold for a while, the freon level is likely not the issue. Your evaporator core could be freezing up. Or it could be an air mix motor issue... Or maybe the brains of the auto climate control. One of the pitfalls with auto stuff in general is the fact that it is harder to diagnose and repair.

 

I'd let a mechanic that is familiar with GM auto climate control look at it. A general knowledge mechanic will likely chase his tail for a while figuring it out.l

[parrdaddy]

My 04 Sierra is doing the same thing, just wondering if you have figured out a fix for it yet? I'm thinking it is an electrical issue somewhere, maybe a bad ground or solder joint somewhere which makes the climate control default to full heat???

[cammiller]

I have had a few trucks lately that have done this and it has turned out to be the mix door actuator. Luckily, both it was the left side control which is on the bottom of the case and easy to get at.

[parrdaddy]

I have had a few trucks lately that have done this and it has turned out to be the mix door actuator. Luckily, both it was the left side control which is on the bottom of the case and easy to get at.

 

Did you replace the actuator, or just reset them?

[cammiller]

I have had to replace them. The feedback sensors fail inside the actuators and cannot be repaired.

[ericguy320]

Fan clutch working?

[cammiller]

I'm sure that if it was a fan clutch, the engine would be overheating.

[apd123]

It kinda sounds to me like you might have some sort of short in your wiring have you tried having a auto electrician lookin at it? I had some work done on mine recently and he found the problem in about 30 min i would say find a good one near you and give them a try to figure it out thats the only thing i can think of

[parrdaddy]

My problem is very random, in has only happened a few times over the last several months. But when it happens, I can't get cold air again until I turn off the engine and restart it. I'm waiting until it happens again to check if the passenger side goes hot too, this one may be hard to figure out.