A/C Electrical Problem -Astro Van

Greetings:

I own a 97 AWD Astro van with 140K miles. The AC unit does not turn on. I had a local mechanic check it out only to discover there is no electrical power going to the unit under the hood. He check all fuses but no luck. He does not do in-depth electrical work. I have to find another person to do this. He did say that perhaps the last person doing work may have accidently cut a wire, diconnected a switch, etc. Speculation only of course.

Last fall I had a local mechanic (different guy) replace the power steering pump. This guy does not do electrical work either unless I can pin point what to look for.

Can you suggest what might be the problem or what we might focus on? Or perhaps there is something else we should do.

Any assitance would be much appreciated.

Thank you.

If by "unit under the hood" your mechanic was referring to the compressor clutch, there could be numerous reasons for that. There is a low refrigerant pressure cutout, a high refigerant pressure cutout, and any number of reasons the Body Control Module would not allow the compressor to run. There is also a relay in the Underhood Electrical Center which operates the A/C compressor clutch. Make sure it is intact.

the number one failure mode in a/c systems is loss of charge- due to a leak somewhere- where the refrigerant drops to a level low enough to not allow the pressure switches to activate the compressor-- so a system pressure check is in order....get some gages and diagnose it.....

Greetings:

The mechanic that check out my AC did have the system connected to hoses and guages. He said the system still had pressure but it was low. He was attempting to add a can of "stop leak" (thinking the reason it did not start was due to being low on freon) and that is when he discovered that the problem was electrical. He did check all fuses, checked and switched around a couple of relays but still the AC system would not start. There is a wire that connects to the black box (left side of vehicle). He pulled that wire to see if there was power. That wire was not providing power. That is why he has determined it's an electrical problem.

Any suggestions as what to look for?

Thanks

"jumper" the wiring connector on the silver accumulator can- this is the pressure cycling switch which will disactivate the system if it does not see 47 psi- if compressor comes on- then system is either below 47 psi (very cold out or low on refrigerant) or switch is bad.....