How can I fix my air conditioning?

You have one of two problems. The heater core is plugged /
restricted or there is an inoperative internal blend door motor problem. Start the vehicle and let it reach operating temperature. Feel the hoses under the hood that go into the heater core. They should be close to the same temperature. If one is hot and the other luke warm/cold.... the heater core is plugged/restricted. If both hoses are near the same temperature, suspect a defective/non operational blend door motor that controls heat/cold/airflow attached to the heater box assembly

2001 Chevy Tahoe Heat Problem - Tahoe Forum

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Dec 5, 2008 - 10 posts - ‎7 authors 2001 Tahoe, the front heater blows a little hot air when the car warms up and then blows cold air. The rear heat seems to work fine. I changed ...

Rear AC blows hot air - Tahoe Forum - Chevy Tahoe Forum

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Jul 14, 2008 - 10 posts - ‎5 authors
On my wifes 03' Yukon the rear air conditioning blows hot air no .... Pull the panel off and look at the hot/cold actuator shown in the picture.

As per your problem mentioned.There are few solved help links to troubleshoot these problems.Go through the list and Click the link below:----
Air conditioner blows air but not cold air http://repairhelpcenter.blogspot.in/2012/07/air-conditioner-blows-air-but-not-cold.html

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Car overheats and Air blows hot at idle? http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

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Heat blows cold on drivers side and hot on passenger side? http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html---------- Hot air on the driver's side vents only? http://repairhelpcenter.blogspot.com/2012/01/hot-air-on-drivers-side-vents-only.html

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2005 Chrysler PT Cruiser: A/C Blows Warm? http://whoisbyme.blogspot.in/2012/06/2005-chrysler-pt-cruiser-ac-blows-warm.html

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1992 Toyota Camry: A/C Control light Flashing and A/C not Blowing Cold? http://technoanswers.blogspot.in/2012/04/1992-toyota-camry-ac-control-light.html

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No heat, blower blows only cold? http://technoanswers.blogspot.in/2012/02/no-heatblower-blows-only-cold.html

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These will help.
Thanks.

What do you mean when you say it wont shut off? is it blowing hot air or do you just feel a lite flow of hot air even if you have the settings to cold?

If this is the problem that you always feel hot air at low flow and the ac goes to hot air then i would say one of two things, first if you have the selector to cold and you feel hot air then there may be a problem with the blend door, this door move to allow hot or cold air, the door may be broken or just a bad motor that controls it. keep in mind if the ac system shuts down for any reason the air then will be warm, it will be about the same temp as outside and maybe a little hotter.

this problem almost sounds like the ac compressor shuts off and then you are getting the outside air which is hot, there are many reasons for the compressor to shut off, it could be the compressor clutch heating up and disengaging , this would be due to a bad compressor clutch.

another reason is the fans are not working, the best thing to do is when the system starts to blow warm check and see if the compressor is running, start engine and look at the front of compressor, with ac off the front of it will not move, and then with ac on the front will spin, check it out and let me know, if it blows warm air and ac is not working then it may be compressor problem but if you are getting warm air and the compressor is spinning then it may be a door problem.

This is hard to check with out testing the system, so i listed a few things to check and let me know the out come. also the ac blows cold for how long before it gets hot air blowing out of the vents, good day.

For this types of problem,i suggest you to check this help links:----Car heater blowing warm, but not hot air?http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html
---------A/C, heater, defroster fan, not working?http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html
--------Heater problem?http://technoanswers.blogspot.in/2012/02/heater-problem-on-isuzu-trooper.html
---------Engine Overheats and heater blowing cold?http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html
-----------Heat blows cold on drivers side and hot on passenger side?http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html----------------This will help.Thanks.

May have to 'flush' out the system, especially if the heater core has 2 hoses at the 'firewall' that are not getting hot when the engine is hot.

If the hoses are getting hot but it's cold inside the cabin, then it's a bad blend door actuator problem.

Good luck on this repair.

It sounds like the dual climate control valve. It is supposed to close the valves when the a/c is turned on, but they get stuck sometimes. I have already replaced 2.

What happens is the valves get stuck and the engine heat will blow over the cool air making it feel warm, even though the a/c is working fine.

If it started out on one side of the car cooling better than the other than you can almost bet this is the problem.

They will be called a heater control valve by most auto parts stores. I think the part is Motorcraft YG378.

Another way to make sure this is the problem is to find the dccv and clamp the two top black hoses with pliers or something and see if the car gets cooler. It will still not get cold but this will let you know if the dccv is the problem.

Have you checked the coolant level? If it's low, it will result in diminished heat, and could be the problem.

it sounds like you have a blend door problem. This is located in the HVAC sysem it closes a door from cold side to hot side. sounds like a bad servo motor or a vacuum leake on that motor. Hope this helps you, please rank this solution

With the car warmed up,feel the heater hoses,are they both warm/hot near the firewall in the engine compartment?If they are both warm/hot,then the heater core should have circulation through it and it may be a "blend door" issue in the heater a/c assembly.If they are not warm/hot then the heater core could be dirty and plugged up and needs to be flushed.
If the above does not help,a drain and vacuum of the cooling system and vacuum refill will remove any trapped air.
Sometimes,clamping off the top rad hose and holding the engine rpm at 2000 rpm will force trapped air out of the heater core.(Watch temp gauge when trying this)
Lastly,a NEW thermostat doesn't mean its working correctly.