GMC A/C Issue

[marshman]

Seems like I have seen a few A/C problems with GMC's posted here recently and now I have one. The A/C on my 04 GMC Sierra for the last couple years hasn't exactly been blowing cold, but if you ran it on high it would be bearable. Earlier this summer while driving it started switching from cool air to hot. Only way to get it back to cool would be to stop, turn off the engine, then re-start. Now the 2 air vents on the passenger side are constantly blowing hot air while at the same time the 2 vents on the drivers side is blowing cool. They counteract each other and it never gets even close to bearable. Turnig off the engine doesn't help anymore. I've heard that it could be an actuator, but is there more than 1? Is this something I could replace or will emptying the refregerant be necessary? What does one of these cost and what would I expect to pay if I took it to a shop? I've heard around $500-600. Does that sound right?

[wacodusm]

I had an 03 that did something like what you described. One day driving it just started blowing warm air when I had the A/C on. It was still under warranty at the time. I took it in and they replaced a 20 dollar relay and worked fine. Hope that is your problem.

[WRsteveX]

My 04 silverado blows ice cold and I've never touched the system. Never added freon, nothing.
It did the hot air thing a few times pretty close together. HOT HOT air. It does it like once every 6 months now. I just push the shifter to N, kill it, and tart it back up.
I haven't done it in traffic, but on a country road once and a hwy. never even stopped. Probably lost 5mph from the speed I was going..

[krisw]

Google blend door for your truck. I think there are 2 on the truck. One actuator is cheap and easy to change. There are a couple of videos on YouTube. See if any of that sounds like your problem

[HoustonR6ryda]

sounds like the actuator -for sure if the pipes are cold and sweating under the hood

[georgec]

There is three actuators under the dash that go bad. I have had to replace all of the ones on my 04. A couple of them can be replaced without removing the dash but it sounds like yours might be the one that they have to take the dash apart to replace. They can run a test at the shop that will tell them which one is bad. There is also a actuator that can go bad that will cause the not cooling a good as it did also.

[georgec]

Boy I type slow two people answered before I got done.

[flywise]

2 blend doors, several videos on YouTube on the fix. 1 is very easy 1 is very tough.
Also( first ) you might want to replace the control switch panel( where the selector knobs are) about $ 139. I bought one and now all my air flows from the vents I want it to. Before I replaced the switch it would blow from defrost sometimes, heater or Ac vents.