Working with a friend on his 1999 Lumina 3.1. The a/c compressor will not turn on, so he tried to put in a can of 134a but no luck. In the old days, we jumped the low pressure switch on the accumulator. This car has a switch by the accumulator, but it has 3 wires instead of two. Can a man still jump the compressor there? Should I hook up a separate lead to the compressor and connect it to the battery to get the clutch to engage?

Monte Heeren

The reason here is the issue, is there freon in system, is the relay good?, What are the static pressures?

I'll check the pressures this weekend and re-post. Thanks for the reply.
Monte

To answer your question about the three wires YOU CAN"T JUMP THE COMPRESSOR. If you try jumping those wires you risk burning the IAC motor out, & almost for sure blow the ignition fuse. The compresor LOW PRESSURE SWITCH is a ground switch. It will active when there is enought freon.

On mine, I went right to the compressor. There is two wires going to the compressor. I used wire strippers and just cut through the insulation on the green wire, then using my thumb-nail pulled back the insulation enough to expose the copper. I used an alligator clip to clip on this spot, and the other end I went right to the positive post. Be carefull, as if the pump is frozen, you will know right away!!!

Do this while checking for pressure. Running a pump with very little pressure for any extent of time can damage it.

From a completely discharged system, one can of freon will usually give you enough pressure so that you should be able to remove the jumper.

Also, make sure your "check engine" light is NOT on. If you get a MAP (air intake) sensor code, that will sometimes prevent your pump from working as well.

Thank you all for the replys. Have not had time to get back at the car yet. I will try the jumper from the battery to the compressor.