Manually Engaging A/C Compressor

Guero · Jun 10, 2008

How do you Manually Engage the A/C Compressor on a 91 GT?

BlownFiveLiter · Jun 10, 2008

Turn the switch on and jumper the harness for the low pressure sensor on the accumulator.

Guero · Jun 11, 2008

You mean turn the AC on right? How do u jump the sensor?

BlownFiveLiter · Jun 11, 2008

You actually want to jump the harness. Unplug it from the sensor and put a piece of wire across the connector. Don't do it if it's an empty system, or you'll fry the compressor.

Guero · Jun 11, 2008

Well I tried and its not spinning!

HISSIN50 · Jun 11, 2008

Guero, if your compressor won't engage for no apparent reason, check the WOT relay and its wiring socket. They are on the passenger fender kinda under the MAF. The wiring is very susceptible to getting baked and causing an open circuit or other issues. Sometimes just moving the relay around in your hand causes the AC to kick on.

Redoing the wiring or splicing in a new socket and relay are the common solutions if this is the issue.

An issue at this junction will cause jumping of the LPCS that Matt talked about to not work.

jrichker · Jun 11, 2008

Get out your voltmeter and check for 12 volts at the low pressure cutout switch that you were told to jumper. No 12 volts, keep on looking...

Diagram courtesy of Tmoss & Stang&2birds

Guero · Jun 11, 2008

Thanks for all your help!

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Manually Engaging A/C Compressor

Guero

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BlownFiveLiter

have car, will race....wait, it doesn't run

Guero

Active Member

BlownFiveLiter

have car, will race....wait, it doesn't run

Guero

Active Member

HISSIN50

"How long does it take to get help in here?

jrichker

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Guero

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