Intermittently A/C not working properly

2002 CHEVROLET SILVERADO
166,000 MILES • 6.0L • V8 • 2WD • AUTOMATIC
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CHIMELAK
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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.
Sep 3, 2021 at 7:11 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 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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Sep 3, 2021 at 10:54 AM
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CHIMELAK
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Pressures are good, not it. Can you give me the supposed voltage from PCM to compressor so I can run a hotwire?
Sep 7, 2021 at 8:33 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 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
Sep 7, 2021 at 8:50 AM
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CHIMELAK
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Not from PCM, got it. What is the voltage that ends up at the compressor?
Sep 7, 2021 at 8:53 AM
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CHIMELAK
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The voltage that energizes the clutch?
Sep 7, 2021 at 8:54 AM
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ASEMASTER6371
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Battery voltage. It should be a minimum of 12 volts.

Roy
Sep 7, 2021 at 9:00 AM
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CHIMELAK
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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?
Sep 7, 2021 at 12:49 PM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 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
Sep 7, 2021 at 9:27 PM
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CHIMELAK
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  • 13 POSTS
Beautiful. thank you very much and God Bless you and your Service!
Sep 8, 2021 at 1:30 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 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
Sep 8, 2021 at 1:47 AM
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