AC not working

Tiny
CINDEE
  • MEMBER
  • 2002 CHEVROLET TAHOE
  • V8
  • 2WD
  • AUTOMATIC
  • 128,000 MILES
Today I got in it to leave from work and AC stopped working. The air is blowing but not cool at all, and I never heard compressor kick on? The radio looks like it has power the light are on but no sound? Before it went out completely it (radio) would work then quit for like a week before it went out all the way? Could this be an electrical problem? Please give me advice where to start looking. Thank you:)
Monday, August 24th, 2009 AT 5:54 PM

35 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
For the AC

Air conditioner blowing warm air only and no cool air? Your A/C cooling problem could be caused by any of the following:

Your A/C system may have lost its charge of refrigerant, or the compressor may not be engaging when you turn on the A/C, or the blend air door inside the HVAC unit may be stuck in the HEAT position so no air goes through the A/C evaporator.

Start with the compressor. Does it engage when you turn on the A/C?

If so, the compressor is working and the A/C system probably contains enough refrigerant to make cold air, so the problem is inside the HVAC unit. Replace the motor that controls the blend air door (this is a difficult job and best left to a professional since it involves tearing apart the HVAC unit -- about an 8 to 10 hour job!).

If the compressor does not engage when you turn on the A/C, see if it will run by jumping the compressor clutch wire directly to the battery (use a fused jumper wire). If the compressor works when you jump it, and the A/C blows cold air, the system contains refrigerant and the fault is likely a bad A/C compressor clutch relay or a bad clutch cycling switch or pressure switch.

If the compressor does not engage when you jump it, the problem is a bad compressor clutch.

If the clutch engages but the compressor does not turn (the belt will start to slip and squeal), the compressor is loced up and you need a new compressor.

If the compressor clutch engages and turns the compressor, but the A/C still does not blow cold air, the system is probably low on refrigerant and needs to be recharged. If you Have an A/C gauge set, hook it up and see if the system has any pressure.

If it is out of refrigerant or is low, check for leaks, then have the A/C system vacuum purged to remove air. After the air is out, it can be recharged with the specified amount of refrigerant. It is important to get any air out as this will reduce cooling efficiency and may make the compressor noisy.

My advice to you if you know nothing about A/C service is to find a repair shop that specializes in A/C repairs and let them fix your cooling problem for you. Today's A/C systems with automatic climate control are very complex and reuire special tools and know-how to diagnose and repair.

Could be the radio fuse/connection or the built in amplifier could be blown
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Monday, August 24th, 2009 AT 6:26 PM
Tiny
E DURRANT
  • MEMBER
  • 1 POST
  • 2001 CHEVROLET TAHOE
Air Conditioning problem
2001 Chevy Tahoe V8 Four Wheel Drive Automatic

A few weeks ago the rear ac quit working and blows only hot air. The front ac works just fine. I am told there is just one system?
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
MR_RWS
  • MEMBER
  • 1 POST
I've run into similar problems with an 03 where the climate control intermittently goes off the deepend or when the vehicle is powered down (battery replaced). Each time the dealer told me sounds like the HVAC needs to be recalibrated. That'll be $200. The last time they told me I needed to replace the actuator. That'll be $1200. That was enough for me.

After a bit of googling I found instructions on how to recalibrate the actuators. Try this and see if it works:

Actuator Recalibration

The HVAC control module will relearn the actuator limits whenever power is disconnected and re-connected to the module.

Use the following steps to perform the calibration update:

Turn OFF the ignition.
Remove the battery positive voltage circuit fuse of the HVAC Control Module.
Important: The scan tool must be disconnected from the vehicle to properly perform the calibration procedure. If a scan tool is connected before this procedure is completed, then new calibration values will not be stored.

Important: Failure to wait 60 seconds will not allow the HVAC control module sufficient time to clear the old calibration values.

Wait 60 seconds.
Install the fuse.
Turn ON the ignition.
Wait 60 seconds before installing a scan tool

Good luck
Mr_RWS
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
RICH_5
  • MEMBER
  • 1 POST
How did this do? Is it working now? My rear ac is working fine; cooling is normal. But, the front ac is blowing hot air. Help.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
COYOTTE82
  • MEMBER
  • 7 POSTS
  • 1999 CHEVROLET TAHOE
  • V8
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
I have this tahoe with a/c problem. I had changed the compressor before because the clutch bearing went out. And the lines to the compressor because they were leaking at the valve. After a couple of months stopped cooling in the front, rear cools but not cold. Pressure on high side was about 200 low side 30 and would go down to 25 before it cycled off. Line was cold were expansion valve is located, goes into the evap cold and comes out warm (if it even comes out). I thought it was the accumulator that was clogged so I evacuated, vaccumed and tried to recharge but can't even put in a can in there, and I forgot to turn on the rear side to see if it would go in. I suspect that is the evap (front) thats getting clogged. I need another opinion from mine.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,251 POSTS
If it's hold vacuum, recharge about 1 can with engine and compressor not running through the high side, then close the valve, then bypass the low prssure cut out switch, usually on the accumulator, then charge through the low side with engine and compressor running. Orifice tubes on the inlet line can get clogged and block the screen, but 200 high and 30 on the low doesnt seem too far off, Low side should read more like 35-40 at 200 high side.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
COYOTTE82
  • MEMBER
  • 7 POSTS
Well I checked for clogs by checking flow through the components, hoses had condenser and evaporator had flow in them nothing clogged and I just replaced the orifice tube, still the rear is cooling but not the front side. Im still puzzled.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,251 POSTS
If low side is still at 30hg try putting in a bit more r134, should be at 35-40. Is it auto temp? If yes get a can of compressed air for computers and blow the air temp sensor clean. The one inside the cabin.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
20THCENTBOY
  • MEMBER
  • 19 POSTS
  • 2005 CHEVROLET TAHOE
  • V8
  • 2WD
  • AUTOMATIC
  • 80,000 MILES
Its a replaced engine that's been in over a year. Just noticed last week no cold air from AC. Tried filling coolant from store bought filler and it acted strange. Doing this I noticed the compressor not cycling. Now I haven't been able to run the max cool on 5 for several years but it still cooled the ride on level 4 from control. I just checked voltage to compressor and got no voltage while the tahoe was running ac high. I have checked all fuses to a AC equipment and found no problems. Relay? Something else I can check? Thanks for a replay in advance.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
COYOTTE82
  • MEMBER
  • 7 POSTS
Ok we are good to go. For some reason the pressure was showing normal when it wasnt full, sprayed the condenserwith water and the pressures dropped and I was able to charge it some more. Thanks
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
So was the system completely empty? Also how much charge did you add weight wise?Unless you start with a empty system you dont know if your over charging it.I know the charge kits give you this gauge that say when its full but you cant tell for sure by pressure if its fully charged you by actual weight charged in the system.You also when you know you have the correct charge weight in the system you need a ac gauge set with the high and low gauges a low one that goes up over a 100 psi to properly trouble shoot it.Also a scan tool that can read live ac data is helpful i did that to find a bad high/switch on the ac system causing the ac compressor to cycle. Also a scan to read ac codes especially if you have auto climate control.Here is a link on our site to help you trouble shoot and a better understanding of how the ac works.Let me know what you find and we will go from there.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,251 POSTS
Ok! Your welcome.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
20THCENTBOY
  • MEMBER
  • 19 POSTS
Hate to say I do not have those tools available to me and I do see how the process can be more than just adding from a store bought refiller, still doesn't explain the compressor not turning or the no power voltage to compressor while the ac is on.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
If you dont know how much is in system and you charge it and put too much in that will cause it to not work correctly. If its under charged that will cause a problem. The high low switch shuts down the compressor if the pressure is too high or too low.I dont know what the pressures or how much charge is in the system?You could have a bad high low switch bad connector to it etc. Also if you have auto climate control I have seen the outside air temp for the system keep the compressor from coming on. The ac system is complex then just adding charge to fix it sometimes. Also you have a blown ac fuse or bad connector or wire to the ac clutch.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
20THCENTBOY
  • MEMBER
  • 19 POSTS
As much of a DIY person that I am I do believe this is just a touch over my realm of fixing but I will pass on all of this to any mechanic I have service it. Thanks for your time.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
SROMAIRE
  • MEMBER
  • 1 POST
  • 2001 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
  • 73,000 MILES
Blows hot air no matter if the control knob is on cool and the a/c is on. I have checked the floor and on the passenger side it is not damp and I can not smell anti freeze.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Can you tell if the compressor clutch is engaged? If not, check circuits at compressor relay in power distribution center. Any codes? Some of the national brand autostores will check some codes for free.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
Alright let me know what you find.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
ONYX959702
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET TAHOE
Air Conditioning problem
2003 Chevy Tahoe V8 Two Wheel Drive Automatic

I changed my alternator now my a/c is not working and the instrument lights for the a/c and rear defroster dont come on. What could be the problem?
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
If your saying the ac blows air but it isn't cool, I'd have to check the compressor clutch, see if it is engaged. If it isn't engaged, I'd check the circuits at the ac relay, two of those terminals should be hot with key on. The pcm grounds the coil side of relay in order to energize. The pcm has to receive an ac request before it will energize the relay. If your low on refrigerant, the pcm may not receive a request.
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Wednesday, April 24th, 2019 AT 7:12 PM (Merged)

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