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Intermittently A/C not working properly

Tiny
CHIMELAK
  • MEMBER
  • 2002 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 166,000 MILES
More not than working.
The only way I can get it to come on is crackpots the windows at highway speed or run up to over 85 MPH. Sometimes it works more often not and from 85 MPH if I coast to 70 MPH. If I put on speed control once it's on it will stay on for a good while.

Can you tell me if there is way to hotwire the compressor? I've replaced the sensors inside and out. It's always fully charged and no one knows how to find it. If they can get it to run at all.
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Friday, September 3rd, 2021 AT 2:11 PM

10 Replies

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

Can you give me the high and low side Freon pressure readings while the AC is on? I want to see if the system is working correctly.

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

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

This could be an issue with the pressures not being correct. From your description, the compressor is working.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

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

Roy
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Friday, September 3rd, 2021 AT 5:54 PM
Tiny
CHIMELAK
  • MEMBER
  • 13 POSTS
Pressures are good, not it. Can you give me the supposed voltage from PCM to compressor so I can run a hotwire?
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Tuesday, September 7th, 2021 AT 3:33 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
What are the pressures? I need those readings.

It comes from the relay, not the PCM. Look at the diagram. Pin 87 of the relay is where the wire runs to the compressor.

You can jump pin 30 to pin 87 and the compressor should come on.

Roy
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Tuesday, September 7th, 2021 AT 3:50 PM
Tiny
CHIMELAK
  • MEMBER
  • 13 POSTS
Not from PCM, got it. What is the voltage that ends up at the compressor?
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Tuesday, September 7th, 2021 AT 3:53 PM
Tiny
CHIMELAK
  • MEMBER
  • 13 POSTS
The voltage that energizes the clutch?
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Tuesday, September 7th, 2021 AT 3:54 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Battery voltage. It should be a minimum of 12 volts.

Roy
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Tuesday, September 7th, 2021 AT 4:00 PM
Tiny
CHIMELAK
  • MEMBER
  • 13 POSTS
Are you 100% sure? I know the power is from the relay but the minimum coming from the relay is 12v? One last question please. If I run a switch 12v from the battery for the compressor, is there a way to incorporate the low pressure switch (if it's not the culprit) with this new switch?
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Tuesday, September 7th, 2021 AT 7:49 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
I am 100% sure.

You can run a wire from the battery to the low-pressure switch. The output from the low-pressure switch goes to the compressor.

You can install your toggle switch anywhere in that circuit.

Roy
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Wednesday, September 8th, 2021 AT 4:27 AM
Tiny
CHIMELAK
  • MEMBER
  • 13 POSTS
Beautiful. Thank you very much and God Bless you and your Service!
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Wednesday, September 8th, 2021 AT 8:30 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You are welcome.

Always glad to help.

Please go to this link and give us a good review.

https://www.sitejabber.com/reviews/2carpros.com

Roy
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Wednesday, September 8th, 2021 AT 8:47 AM

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