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A/C not working?

Tiny
JON RICE 68
  • MEMBER
  • 2013 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 137,000 MILES
When A/C was working it would run about and hour then freeze up then all of a sudden A/C clutch wont engage. Check fuses and relay; they are good but no power to fuse. I was going to test low pressure switch but cant find it to jump it out.
Saturday, July 11th, 2020 AT 8:57 PM

23 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

The low pressure switch is on the accumulator. See pic 1. If you look at pic 2, it shows the fuse for the AC compressor. Is there power to any of the fuses near it? I ask because power to that circuit is right from the battery. See pic 3.

This guide and video can help as well

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

and

https://youtu.be/4UjfQKvrB6Y

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.
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Saturday, July 11th, 2020 AT 9:28 PM
Tiny
JON RICE 68
  • MEMBER
  • 2 POSTS
Hi Joe. Yes, there is power all around the fuse and on my 2013 the low pressure switch is not on the accumulator. Any other ideas where it might be? It's a GMC Sierra 4x4 LST.
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Wednesday, July 15th, 2020 AT 6:44 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

I attached three pics below. This is all there is for this vehicle. If the pressure switch isn't on one of the locations, let me know.

Joe
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Wednesday, July 15th, 2020 AT 3:22 PM
Tiny
FOURFIFTYSL MERCEDES
  • MEMBER
  • 2 POSTS
  • 2007 GMC SIERRA
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
I changed the left blend door (bottom center actuator) now the compressor will not run. I can trip the clutch relay and it runs and gets cold. The refrigerant press s/w shows 1.3 volts the accumulator press s/w is made. There is no ground signal to clutch relay.
The vents have warm air once the engine warms up. A/C is charged. It use to blow cold until the left blend door would act up, then turning the ignition off and on would reset it. I have done the fuse remove reset. No change.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hello,

Something must have happened to the controller or compressor relay. Here is a wiring diagrams (below) and a guide to help you do some testing.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

See if the unit is getting power and that the relay is working and check the fuses

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken

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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
FOURFIFTYSL MERCEDES
  • MEMBER
  • 2 POSTS
The clutch relay works, it dosent get a grnd. Sig from the computer. What should the return voltage be at the refrigerant
press. Switch. It gets the 5v looks like it returns 1.3v and the ground is good.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Try to use a jumper on the pressure switch connector to see if the compressor turns on.

, Ken
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-1
Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEVIN ROBERTS2
  • MEMBER
  • 4 POSTS
  • 2006 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 129,000 MILES
The AC starts to blow warm after about ten minutes on both sides. It has the automatic control on it. I am assuming actuator door but could be completely off base.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
The first thing that you need to do is get the A/C refrigerant pressures tested to make sure that they are with in specs, this will help with the diagnosis.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEVIN ROBERTS2
  • MEMBER
  • 4 POSTS
I did get those tested last fall when this started and they appeared to be fine.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Can you look to see after it starts to blow warm air if the compressor is still engaged and turning?
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEVIN ROBERTS2
  • MEMBER
  • 4 POSTS
It seems to be. I was looking at it last night trying to do the "actuator reset" people were doing online. After the reset it was still blowing warm air and the compressor seemed to be on and the lines were freezing cold to the touch.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Sounds as if the blend door is defaulting to hot. Can you tell if the blend door is actually working at all? It may be stuck on warm and as the engine heats up you start getting the warm air blowing.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEVIN ROBERTS2
  • MEMBER
  • 4 POSTS
Would it be the one under the dash on the passenger side? I can work on getting the cover off tonight and taking a look. Can you visually see if it is moving without removing it? Or is there a way to know if it is functioning correctly?
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
I have never pulled one apart on that model unfortunately, but normally you cannot see anything as the actuator drives the gear on the end shaft and it is all internal of the heater box. In dealerships, they can for the most part, use factory scanners to watch the actuator working electronically. You should be able to hear the actuator drive the door open and closed. You can use a length of rubber hose say about 1/4'' or so as a stethoscope and listen in and see if you can hear the motor drive the door open or closed.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
MIKEIMHAUSEN
  • MEMBER
  • 1 POST
  • 2006 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 177,000 MILES
Just recharge coolant is full compressor kicks on and off does not stay running consistently no cool air coming from
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hello,

It sounds like the system is overfull causing the high pressure cut out sensor to kick in. To be sure here is a guide to help you check the high side pressure its should be about 250 psi on a hot day:

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

Please run down this guide and report back.
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Friday, December 18th, 2020 AT 9:40 AM (Merged)
Tiny
PAUL RICHARDS
  • MEMBER
  • 1 POST
  • 2003 GMC SIERRA
  • 6.6L
  • V8
  • TURBO
  • 4WD
  • AUTOMATIC
  • 270,000 MILES
A/C clutch stays engaged but no cooling. And no hot high pressure or cold low pressure lines with feel.
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Friday, December 18th, 2020 AT 9:42 AM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
That is not a good sign. The first thing you need to do is use a set of professional gauges and record high and low pressures both at idle and at 2,000 rpm. We can go from there but there are many, many factors that are taken into consideration is diagnosing an AC system.

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

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon
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Friday, December 18th, 2020 AT 9:43 AM (Merged)
Tiny
LINDCALL
  • MEMBER
  • 1 POST
  • 2002 GMC SIERRA
  • V6
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I was told it was the blend door actuator. It is right under the passenger side. Is there any adjusting or simple remove & replace? Is the correct part dorman 604-106 / oem 89018365?
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Friday, December 18th, 2020 AT 9:43 AM (Merged)

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