Why does my AC suddenly start blowing hot air?

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

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

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.

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.

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....

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.

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

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?

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?

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.

THERMOSTAT

It's actually the blend door actuator not the thermostat

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

Relearned mine and it worked AWESOME! THANK YOU!

Relearned!! Working good so far. 2004 Yukon 5.3 cold driver side hot passenger side Both cold now thanks. 6/2/17

where does the wires for the actuator plug in ?

I'm hot!

I replaced the blend door actuator today on my 2004 Yukon in less than 2 hours and that included going to O'Reilly's to purchase the part. The most difficult part is removing one of the screws (one of three) in the cover under the passenger side dash. Followed these instructions: https://www.youtube.com/watch? v=vdw0OOAku4o. Listen carefully and you will hear him say he only removed two screws as the third screw was removed 10 yrs ago and it was so hard to remove, he left it out. You DO NOT have to remove the center console to remove the cover.

I have had the same issue on my 2005 Yukon Denali for a while. Turning it off then back on has helped. However, the actuator seems to be a common issue with everyone. Thanks for the insight. Wonder why GMC hasn't done a recall to fix this issue?

David, you're a legend for sharing your tip. I just relearned mine exactly as you suggested on my 2004 Tahoe and it has fixed my passenger side which was blowing hot. Thank you so much!

UPDATE: I spoke too soon and my problem came back once I restarted the car. I found this fix and tried it. It worked! Hopefully more permanently this time! http://sparkys-answers.com/2011/08/hvac-actuator-recalibration-procedure.html

2004 GMC Yukon XL Thanks for the suggestions. I tried both solutions without success. Hopefully one of these options work for others. In my case, the cold air comes out of both front left and right for about 1 minute before going to boiling hot. The rear A/C continues to blow cold.

2007 Yukon blowing hot and cold air what's the problem. unplug the high low switch jumped it with a paperclip and the compressor turned on.

I have had 2 Chevrolet’s that have had this problem. One was new under warranty and Chevrolet didn’t fix the problem, totaled that vehicle. They said they couldn’t fix it because it didn’t do it while it was there. Our 2005 Silverado still does this.

My answers is don't buy GM cars n trucks I've had more problems with my 2004 Silverado than all my other cars n trucks put together including this one with the AC oh have you had to replace your brake n fuel lines yet 1200 hundred dollars if you live where it snows you will there made out of tin

Hello, ive been reading all the questions and answers and I have a similar situation but, with a slight difference. The whole car blows hot air when the air is on but it will also overheat. I smell antifreeze but there are no leaks and the carpets are dry .. Please help. so many possibilities and info

Fan clutch

A temporary solution for my 2005 Silverado is to stop the vehicle turn it off for a couple of minutes then restart, it should reset then & be OK for a while. A long term solution is change the blend door actuator which sells for under $30.00 usually. Check You Tube for instructions.

Relearn didn't work for my 03 Tahoe and I changed the actuator over 6 months ago

If your suburban are car blowing hot air out of the driver side change both of the actuators on the passenger side and the driver side also change the 20058 AC pressure cycling switch under the hood where you add the Freon it’s like a little sensor and then add Freon I guarantee it will work only paid $50 for parts off Amazon and it works like a charm I have a 2007 Chevy suburban the dealer wanted to charge me $1000 to fix well I fix it and cold freezing air hope this help Tks....

I have a 2005 GMC Yukon also. My problem is it not as cool as it use to be. I have change the blend doors all of them and also change the temp controller. Freon pressure is ok. Need help on this,

Remove the lower passenger black plastic sheild. Remove blend door actuator unplug. Turn the black plastic stud with your fingers to left or right. Depending on hot or cold. Easy fix. The 5 minute reset didnt work me. Look at my picture

How did you know what way to turn it? Mine is stuck on hot. Plenty of Freon-Also if there are 2 in the front( 03 Yukon with auto front and rear ac) I located the 2 in the back, and one under the glove box to the left on the passenger side, Where is another one? Or does it control both the air type of flow( hot or cold) and which vents it comes out of?( mine Don’t come out the dash face just defrost and side and rear vents. Thanks