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Air conditioning not working correctly?

Tiny
GEOFFPEARL
  • MEMBER
  • 2015 GMC YUKON
  • 6.2L
  • V8
  • 4WD
  • AUTOMATIC
  • 70,000 MILES
We have the SUV listed above XL Denali. We turn on the air conditioning and cold air blows in the rear and warm air blows in the front vents. Left to right works properly and all modes work properly.
Sunday, May 26th, 2019 AT 8:38 PM

56 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

This sounds like the system is low on charge this video and guides will wil you fix the problem.

https://youtu.be/uZrQCGwXfek

and

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

and

https://www.2carpros.com/articles/replace-blend-door-motor

Please run down these guides and report back.

Roy
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Monday, May 27th, 2019 AT 1:48 PM
Tiny
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  • 31 POSTS
It doesn’t make sense that the rear vents would be blowing cold and the fronts warm.
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Monday, May 27th, 2019 AT 6:50 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Yes, it does. The rear has its own expansion valve and the front has its own as well.

I need the gauge readings to help

Roy
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Monday, May 27th, 2019 AT 6:58 PM
Tiny
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  • MEMBER
  • 31 POSTS
I have seen a lot of people suggesting valve door actuators. Can you please point me in the right direction on what gauges to buy/borrow and how to take the high and low side reading?
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Monday, May 27th, 2019 AT 7:09 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You can rent a set of gauges at a parts store or buy a cheap pair at Harbor Freight.

There are ports on the AC lines to attach. You cannot mess up on installing on the ports.

Run the engine with the AC on and tell me the readings on the red gauge and the blue gauge.

Roy
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Monday, May 27th, 2019 AT 7:12 PM
Tiny
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I also recharged it with one of those cans form auto parts store and no dice.
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Monday, May 27th, 2019 AT 7:19 PM
Tiny
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  • MEMBER
  • 31 POSTS
Okay. I will check in again tomorrow night. Thank you.
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Monday, May 27th, 2019 AT 7:19 PM
Tiny
ASEMASTER6371
  • MECHANIC
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You are welcome.

Always glad to help.

Roy
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Monday, May 27th, 2019 AT 7:26 PM
Tiny
GEOFFPEARL
  • MEMBER
  • 31 POSTS
Okay. I have zero pressure in low side. I never heard the compressor or condenser kick on. Whichever is supposed to.
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Tuesday, May 28th, 2019 AT 5:55 PM
Tiny
GEOFFPEARL
  • MEMBER
  • 31 POSTS
I charged it with one of those A/C pro cans and now I’m reading about 29 on the low side. After a minute or two it is dropping to 25.
Video (Click to make bigger)
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Tuesday, May 28th, 2019 AT 6:18 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
That means you had no freon in the system.

You have a leak and you need to find the leak in order for it to work properly.

https://www.2carpros.com/articles/air-conditioner-leak-detection

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Roy
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Tuesday, May 28th, 2019 AT 6:32 PM
Tiny
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  • 31 POSTS
I think I found the stupid leak. Looking through the grill, I found this in the top right corner of condenser.
Image (Click to make bigger)
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Tuesday, May 28th, 2019 AT 7:43 PM
Tiny
ASEMASTER6371
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Yep, that's the leak.

Replace the condenser and the dryer and evacuate and recharge.

Roy
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Tuesday, May 28th, 2019 AT 7:53 PM
Tiny
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Thank you so much!
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Tuesday, May 28th, 2019 AT 8:01 PM
Tiny
GEOFFPEARL
  • MEMBER
  • 31 POSTS
Replaced condenser and dryer. Pressure is reading about 45 after recharging it with a r134a can and it still isn’t very cold.
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Thursday, June 6th, 2019 AT 1:27 PM
Tiny
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Do I need to evacuate the lines first?
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Thursday, June 6th, 2019 AT 1:28 PM
Tiny
ASEMASTER6371
  • MECHANIC
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How much did you add?

Did you replace the dryer? That is required.

How long did you evacuate the system?

Roy
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Thursday, June 6th, 2019 AT 1:29 PM
Tiny
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  • 31 POSTS
I added a 12 ounce can then another maybe 4-6 ounces. I did replace the dryer too. I did not evacuate but it seems to be blowing colder now. At least cold enough that my wife isn’t complaining. :)

What does evacuation do?
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Thursday, June 6th, 2019 AT 2:53 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Boils all the moisture out of the system. If you have moisture, it will not produce enough cold air.

Roy
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Thursday, June 6th, 2019 AT 3:02 PM
Tiny
ROY RISTER
  • MEMBER
  • 1 POST
  • 2011 GMC YUKON
  • 6.2L
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
A/C is blowing cold everywhere other than passenger side of vehicle. Same when you run heat most of the time it blows warm but other times cold only. Have changed the drivers side blend door and cannot locate passenger side. Any help is appreciated, wife is complaining!
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Thursday, July 16th, 2020 AT 11:41 AM (Merged)

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