How to Jump AC Compressor?

[Overlord475]

After replacing all O-rings, high / low pressure switches, and dryer I vacuumed down my AC.

Began charging the system and it took one 12oz can. Both high and low sides are showing 75psig.

The compressor will not kick on in order to accept more.

I've disconnected both high and low pressure switches and jumped them to try to get the clutch to engage but it has not worked.

What is the proper way to jump the compressor clutch to force it to engage?

Should I disconnect the pigtail going straight to the compressor and supply 12v?

Thanks.

[e30rapidic]

***to test the clutch***

disconnect pigtail....supply 12V from the battery....listen for the CLACK

[jlevie]

If you have shorted both the high and low pressure switches, there's a problem elsewhere in the compressor control circuit. You could jump power directly to the compressor clutch, but before A/C will work you will have to diagnose the basic problem.

[Overlord475]

Figured it out.

For future reference here is how to force the clutch to engage:

On the car side the Red/Blk wire going to the 3 prong pigtail sees 12v when the high & low pressure conditions are met. Or you can just put a jumper wire on the car side of the high and low pressure switch terminals.

To jump the compressor clutch 12v needs to be supplied to the corresponding prong on the compressor side of the pigtail (black wire). No ground is needed as the compressor clutch and diode each ground out on the compressor housing itself.

My issue turned out to be a bad ground on the compressor for the clutch itself. There is a very small green wire on the back side of the clutch. Make sure that it is secure.

Secondly, make sure that at the compressor 3 prong pigtail each one of the individual wires is pressed in and make a solid connecting with the other side of the connector.