Intermittently cold air will blow for a few minutes?

Tiny
CMANGUM
  • MEMBER
  • 2011 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 114,000 MILES
Intermittently cold air will blow for a few minutes. I check Freon and low side reads avg around 50 and high side does not read. I have tried to add Freon and it seems to be full. The compressor does cycle off and on. I evacuated the system and pulled a vacuum on the system and it held 28 for over 12 hours.
Sunday, May 12th, 2019 AT 4:54 AM

58 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Hello,

If the compressor runs with refrigerant inside and does not build pressure the compressor has gone bad here is a guide to help walk you through the steps of replacing the it and recharging the system with diagrams below to show you on your truck.

https://www.2carpros.com/articles/replace-air-conditioner-compressor

and

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

Check out the diagrams (Below). Please let us know what happens.
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Tuesday, May 14th, 2019 AT 11:06 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi Cmangum,

More than likely your high gauge is reading a very small amount of pressure but due to it being a higher pressure gauge it looks like it is not reading. If you have pressure on the low side, you will have some amount of pressure on the high side. More than likely it is pretty close to being even pressure on low and high side which basically means you compressor is not building pressure. The fact that you pulled it down and it held a vacuum shows there is no leak but the compressor itself is not building pressure. Any time the compressor is cycling but no pressure is building, it typically means the compressor is not doing anything but spinning. There is a slim chance that you have a complete restriction but that normally always presents itself as a very high pressure on the high side.

I included the procedure to replace the compressor because based on this info, that is the direction it appears to be going.

Let me know if I am missing something or didn't understand what your issue is. Thanks

https://www.2carpros.com/articles/replace-air-conditioner-compressor
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Tuesday, May 14th, 2019 AT 11:32 AM
Tiny
514
  • MEMBER
  • 1 POST
  • 2011 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
AC does not work. Compressor does not engage. Shop says the relay is good. That is as far as they got. They suggested that the wire is shorted somewhere between the Low pressure switch and the relay. The shop does not have a good electrical guy so they source this type of stuff out. I decided to try myself if I can find the time. Does this sound right or should I be checking the wires replacing/testing the switch? Or looking elsewhere? Anyone know how?
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Friday, April 30th, 2021 AT 1:21 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,870 POSTS
This sounds like the compressor has gone out or the system is low on charge or a fuse is bad, these videos and guides can help us fix the problem with diagrams below to show you how on your car. I have included (below) the air conditioner wiring diagrams as well so you can see how the system works.

https://youtu.be/4UjfQKvrB6Y not working

and

https://youtu.be/uZrQCGwXfek recharge

and

https://youtu.be/yrhWKlQEPWw leak detection

and

https://youtu.be/4EqdrBVb0sY vacuum and recharge

and

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

Let us know what happens and please upload pictures or videos of the problem.

First you have to determine why the compressor is not engaging before you will know what to look for. All AC systems have some means of disabling the compressor if the system pressure gets too low. If there is a big enough leak, the compressor could put the system into a vacuum, and that could draw in outside air. The humidity in that air combines with refrigerant to form an acid that will attack metal parts. Once the system is recharged, that moisture will circulate and freeze at the orifice tube or expansion valve. That ice will stop the flow of refrigerant until it melts. That typically causes intermittent loss of cooling that can last up to an hour.

There is a low-pressure cut-off switch or a pressure sensor that disables the compressor. The place to start is by measuring the system pressure. If it is low, you will need to search for a leak, then recover the refrigerant that is left in the system, then recharge it with the amount specified.
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Friday, April 30th, 2021 AT 1:21 PM (Merged)
Tiny
JUSTIN1584
  • MEMBER
  • 2 POSTS
  • 2008 CHEVROLET SILVERADO
  • 6.6L
  • V8
  • TURBO
  • 4WD
  • AUTOMATIC
  • 300,000 MILES
Ac is getting cold and working good while driving but hot when rpm's drop and idling at night. Replaced clutch on cooling fan compressor replaced. Somebody told me it could be office tube? Or somebody please tell me how to get it running right I sleep in truck at night I’m a RV transport driver.
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

Do you have gauges to test the high and low side pressures? I need those pressure to see if the system is working correctly.

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

Check the condenser in the front to be sure there is no dirt or debris in the fins. Clean them out if there is any debris.

Try spraying some water on the condenser and see if the cold air returns.

Roy
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
JUSTIN1584
  • MEMBER
  • 2 POSTS
I know it’s showing high on the high side is all I was told. When they spray the condenser it got colder at idle. So they replaced the temperature blend door that fixed it.
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
SLEDBOY2K
  • MEMBER
  • 39 POSTS
  • 2006 CHEVROLET SILVERADO
  • 6.6L
  • V8
  • TURBO
  • 4WD
  • AUTOMATIC
  • 50,000 MILES
I have auto climate control and AC will not turn on, can't get compressor clutch to engage. I have tested and replaced relay and fuses, tested low pressure switch, jumper switch. System is charged and ready. Not getting any power to the compressor. I do have issues with the ambient temperature on the mirror, it goes up while driving to about 30 or 40F higher than actual if that is in any way relevant to the situation. I've tested voltage at connection on top of compressor 0v running and not running.
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Hello,

It sounds like the compressor is out the relay is not working here are two guides to help us see whats wrong and how to fix it.

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

and

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

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
SLEDBOY2K
  • MEMBER
  • 39 POSTS
I found that my ambient air temp sensor had fallen and was contacting the radiator, I assume that might be why the temps were so far off. I have verified that I have plenty of refrigerant in the system and all fuses and relays are tested good. I still cannot get any voltage at the compressor. Does the BCM have anything to do with climate control, ECM
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
No, the PCM has control of the compressor relay.
You need a scan tool that can look at data so you can see what pressure the sensor is sending to the PCM. They fail quite often and cannot be jumped out.

https://www.2carpros.com/images/external/119996296.jpg.gif
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
SLEDBOY2K
  • MEMBER
  • 39 POSTS
I pulled the hvac fuse and waited 30 seconds and then started the truck the truck. Ac came on and now working. Tip I read online someone did. I dunno. Thanks for your inputs
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
What you did is clear the code memory in the HVAC. Whatever code set the first time may set again and then again you may have already resolved the issue so time will tell.
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
SLEDBOY2K
  • MEMBER
  • 39 POSTS
Ok. So when it stared cycling, I threw my gauge on the low side port and when the compressor kicked on, the pressure dropped from 40 to about 15psi then the compressor cycled off and the pressure returned to the green zone at about 40psi. So I replaced the relay and the problem is fixed cost me $34.00
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help.
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Friday, April 30th, 2021 AT 1:23 PM (Merged)
Tiny
MSANFORD8072
  • MEMBER
  • 1 POST
  • 2006 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
When you first start the truck the A/C clutch kicks in the kicks out a few seconds later and wont come on again.
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Friday, April 30th, 2021 AT 1:24 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Welcome to 2CarPros.

Have you checked if it was low on Freon? If it is, this can happen. Take a look through these links and let me know if they help.

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

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

Let me know what you find or if you have other questions.

Take care,
Joe
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Friday, April 30th, 2021 AT 1:24 PM (Merged)
Tiny
MSANFORD8072
  • MEMBER
  • 1 POST
Was blowing cold and suddenly stopped. No sign of leak, replaced the compressor relay bam! All fixed.
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Friday, April 30th, 2021 AT 1:24 PM (Merged)
Tiny
NBATES50
  • MEMBER
  • 2 POSTS
  • 2005 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 157,000 MILES
AC was working great, then over a period of a week or so diminished until now it just blows hot air. The compressor cycles off and on when I turn the air on, it will run for about three or four seconds, then off for about ten or twelve seconds. Over and over. Everyone says it is out of refrigerant, but I am not so sure.
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Friday, April 30th, 2021 AT 1:24 PM (Merged)
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I am Danny.

It sounds like you might be having a problem with the air temperature actuator. It is located on the HVAC unit under the dashboard. It is an electric motor that controls air flow through a door using different ducts. I have attached a picture (circled in red) and tutorial on how to replace. Hope this helps and feel free to ask any questions if needed. Thanks for using 2Carpros.
Danny-

https://www.2carpros.com/articles/replace-blend-door-motor
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Friday, April 30th, 2021 AT 1:24 PM (Merged)

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