A/C now blows hot

gregster2004 · Jul 16, 2018

On my 2004 Yukon Denali with 128,000 miles, the A/C has worked fine, but within a few seconds, it went from cold to now blows hot. It is hot down here in Florida, but this is like I turned it on heat. I have spent $2300 on my other car, and so do not look forward to more on my Yukon. Does anyone know what might cause this to happen? If it were blowing outside air, I would think some component in the A/C broke, but hot, as in HOT? Very confused.

iamdub · Jul 16, 2018

Maybe the blend door actuator took a crap or the rod broke loose or gear stripped? I know there are known issues with the blend door actuators on these things. Hopefully, the A/C still works and it's just a matter of the chilled air not being directed into the cabin. Or maybe the temp control on the dash failed and it defaults to telling the blend door to go to full hot. Pop the hood and see if the compressor is still running. The bigger of the two hoses going to the evaporator will be cold and maybe wet. This will at least let you know that the A/C system is still functional.

swathdiver · Jul 16, 2018

Greg, as Chris spoke of, there are four actuators for the AC up front, have both sides gone hot? It is probably the actuator under the dash on the driver's side. Do you have access to a Tech2 or an advanced scan tool? The Tech2 and the like can read the internal trouble codes and even test and command those actuators back into position.

Maybe someone will know if your year's actuators can be reset manually or if they require the Tech2. You're on the wrong coast or I'd be able to help ya!

Doubeleive · Jul 16, 2018

ya like chris mentioned after you have had the ac control turned on for a few minutes pop the hood and reach inside on the passenger side where the evaporator is near the firewall (looks like a silver tank with tubes coming out of it) and see if it feels cold or is warm that's you first sign, if it is warm then either you have a leak or the compressor has a problem or something of that nature if it is still cold then you may have a actuator problem.

*another thing to check is make sure the belt is still on the compressor, if the belt broke it could be a simple cheap fix with just a new belt, if the belt is not broken but is just hanging there then it could mean the compressor has a problem froze up and kicked the belt off, or if your lucky the belt just came off on it's own.

iamdub · Jul 17, 2018

Doubeleive said:
ya like chris mentioned after you have had the ac control turned on for a few minutes pop the hood and reach inside on the passenger side where the evaporator is near the firewall (looks like a silver tank with tubes coming out of it) and see if it feels cold or is warm that's you first sign, if it is warm then either you have a leak or the compressor has a problem or something of that nature if it is still cold then you may have a actuator problem.

*another thing to check is make sure the belt is still on the compressor, if the belt broke it could be a simple cheap fix with just a new belt, if the belt is not broken but is just hanging there then it could mean the compressor has a problem froze up and kicked the belt off, or if your lucky the belt just came off on it's own.

I had an A/C belt shred to fibers on a nearly-new Express van. A tiny pebble got wedged in one of the pulley's grooves and cut the belt.

mgbgene · Jul 23, 2018

Try doing a reset where you pull the fuse, I can't remember the exact sequence but go to youtube there are several good clips on this problem. More than likely a actuator quit working. I have been thru hell with my a/c. Mine all started when I got a new battery from Autozone and they didn't put a back up battery supply when they pulled the cables off, down hill after that.

latvius · Jul 23, 2018

Did you make a hard left turn before it changed to hot air? Mine used to do that then after it re calibrated it would would blow cold. Turned out to be a broken blend door as the turn would cause it to swing the wrong way.
I used "heater-treater" and fixed it once and for all. (basically a kit to make it single zone and beef up the door)

Lcky 4 · Aug 4, 2018

start with the simple things, check the compressor belt, low side pressure port of the A/C system for low side pressure. It may just be low, but if it empty or really low there may be a leak in the system. also take the time and clean all of the condensers and radiator. Also check to make sure the fans in the engine compartment are working? It could be just a simple fan clutch.

PatDTN · Aug 28, 2018

Mine just did this today. Passenger side and rear ac blow plenty cold. I need to look at the reset procedure. FWIW I disconnected the battery a couple days ago while replacing my oil pressure sensor.

michiganlebnani · Sep 29, 2018

I have 2007 GMC YUKON and i am experiencing the same failure mode. AC blows hot on driver side and cold on the right and rear. I replaced the blend door actuator that is over the transmission hump and that did not fix the problem. i even tried to move the rod manually by hand and still no cold air on the driver side.
i checked the other actuator that is on the driver side but thats only direct the air up or down or bilevel... no issues. i am learning that there is additional 2 actuators one behind the air bag on the right side and another behind dash on the top of the HVAC housing.... have to continue testing and see !

A/C now blows hot

gregster2004

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iamdub

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swathdiver

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Doubeleive

Wes

iamdub

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mgbgene

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latvius

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Lcky 4

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PatDTN

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michiganlebnani

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