A/C clutch only spins when i jump the relay

1997 CHEVROLET TRUCK
280,000 MILES • 4WD • AUTOMATIC
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AUGIE DELIA
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I recently replaced the compressor due to a slight leak. I recharged the system and have adequate pressure but not the clutch won’t engage. When I jump the relay, it works and the air gets cold but once I pull the jumper, nothing. I have tested the relays and gotten a new one and it doesn’t work. Looking for any help I can get.
Oct 16, 2021 at 4:21 AM
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ASEMASTER6371
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Good morning,

I would double-check your work. The high-pressure switch at the bottom of the compressor may be the issue. Check for voltage with the key on. You should have power on both terminals with the switch plugged in.

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

I attached the wiring diagram for you of the system. The connector of the switch was an issue back in the day. Without that signal from that switch, the relay will not close and allow compressor operation.

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

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

Roy

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Oct 16, 2021 at 6:03 AM
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AUGIE DELIA
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Thank you! If that was the issue wouldn’t it still not work when I jumped the relay?
Oct 16, 2021 at 11:29 AM
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ASEMASTER6371
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Nope, the relay sends direct power to the clutch.

Without the proper signal from the switch, the control side of the relay will not energize.

Roy
Oct 16, 2021 at 11:50 AM
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AUGIE DELIA
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Do I need to completely remove the compressor and remove all the Freon from the system to check this?
Oct 16, 2021 at 12:28 PM
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ASEMASTER6371
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No, it is at the back at the bottom. It is tough to get to but take your time.

Roy
Oct 16, 2021 at 1:19 PM