Why does my AC suddenly start blowing hot air?

Asked by Jul 29, 2013 at 09:18 AM about the 2004 GMC Yukon

Question type: Maintenance & Repair

I have a 2004 Yukon with 160000 miles and about a year ago the AC would suddenly blow hot air just on the driver's side while the passenger side still blew cold. After a few weeks it then stating blowing hot air on both sides. The only way to correct it was to turn the car off and back on and then it would immediately start blowing cold again. This happens intermitently. Sometimes go 30-40mins with it blowing cold and then suddenly hot air and sometimes just 5-10mins. Recently I changed the pressure switch and and checked the pressure. The pressure was good. I am not sure if the pressure switch had anything to do woth this but immediatley after changing the switch, when the system would stop blowing cold air it was just the driver's side again and not both. Any insight would be greatly appreciated.

13 Answers

450

Did you find out the exact issue? My 05 Yukon XL does the exact same thing.

45 out of 45 people think this is helpful.
2,000

FIXED IT!!! The blend door actuator has some grease on the contacts inside it. A simple fox. See how to do it here==> http://www.tahoeyukonforum.com/forum/showthread.php?t=17741

196 out of 196 people think this is helpful.
390

You must relearn your actuator to blow hot or cold correctly. Turn on your A/C to the highest blower setting and let it run 5 minutes, then dial up the heat leaving the blower in highest position for five minutes. this should resent your actuator to correctly blow hot or cold. ..that's one way to fix it. I unplugged the old actuator planning to install my new one and decided to wait till the next day. I plugged the old actuator back in and drove to the store and it blew cold air all the way and has not blown hot for over two months now. I even got a refund for the new one I had bought. Remember, if you blowing cold or hot air the actuator is working..but it's out of sync..try these things before wasting your money on a new unneeded part.

39 out of 39 people think this is helpful.
40

I relearned my actuator like David said and my AC works fine. I sat in the truck for twenty minutes to test it out and it did not blow hot air. Will see if problem persists tomorrow. This happened on a 2005 Chevy Silverado 1500 4.3 Liter.

4 out of 4 people think this is helpful.
220

I tried the relearning but the thing wouldn't stay cold for 5 minutes!! I found the directions to clean the actuator but it assumes one knows where the heck that is? Can you point me in the right direction? is this something I can reach without dismantling the dash? I'm in a 2002 suburban--same issue as the Tahoe, Silverado, 1500, seems like most Chevy trucks over 10 years old....

22 out of 22 people think this is helpful.
80

Here is my situation on 2012 GMC Acadia. Drivers side vent-hot Drivers side middle-hot Middle middle-cold Passenger middle-cold Passenger side vent-cold Tried relearn trick no change. Plenty of power coming out of vents, def both very hot and reasonably cold. Any suggestions? I have read so much it's all overwhelming, any easy things to try or look for? How easy/hard to change the actuator and I assume you would only need to change drivers side? Sorry everyone car newbie, I appreciate ANY feedback.

8 out of 8 people think this is helpful.
40

Yes it worked! My Car is a tahoe 2009 cherlot and it worked thank you!

4 out of 4 people think this is helpful.
80

When I turn the a/c on in my 2004 tahoe it blows hot air out the vent for about 10 seconds and then it goes up to the defroster and blows nothing but hot air. I took it to the shop to get the a/c charged and they said it's already charged just not switching over from heat to a/c. Do I have to replace the air temperature control?

8 out of 8 people think this is helpful.
10

My 05 Chevy Suburban started doing that And there are 3 separate controls one for front one for mid row and one for third row seat, front won't work at all back two only blow heat. Any idea what that's about?

1 out of 1 people think this is helpful.
40

My 2005 Tahoe hava AC giving hot air problem. AC would suddenly blow hot air just on the driver's side while the passenger side still blew cold. The only way to correct it was to turn the car off and back on and then it would immediately start blowing cold again. This happens intermitently. Sometimes go 30-40mins with it blowing cold and then suddenly hot air and sometimes just 5- 10mins. Somebody told me to change THERMOSTAT. Plz. advise.

4 out of 4 people think this is helpful.
40

THERMOSTAT

10

It's actually the blend door actuator not the thermostat

10

Look up which is the best for your vehicle some people are able to reset theirs without having to buy a new one and each brand / type vary so if yours can't be reset make sure to bring yours to match the new one As it isn't working it can be unplugged and removed to match the new part

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