I have a 1995 z/28. I recently overhauled my a/c system. New drier(accumulator) and expansion valve (and o-rings etc) Vacuumed the system to 30 MM/HG and fully charged. The a/c clutch will not engage by itself. I have to jump the relay. When I do all works fine.

Couple of questions...

Could this be my low pressure switch?
(I have the 3 pronged one which I can't seem to get anywhere because it apparently doesn't exist)

How can I test the switch?

Do I have a high pressure switch? (No HP switch is listed for this car)

Can I just jump (bypass the switch) the connector to get the system running? or will it not cycle properly (or do I have the variable displacement pump)

If so, How would I jump the connector

Thanks a million...

 

I'm 99% sure there is a low and high pressure cutoff switch. or else, **** would explode, haha.

and yes, if the switch is stuck, the clutch will not cycle. the way id test the switch is by simply bypassing the switch, and if the A/C works, then you have a bad switch

A low pressure cycling switch is designed to open (create an open in the a/c clutch circuit) at a pressure of about 20psi or less. thats 20psi in the a/c system, meaning a very low charge.

The high pressure switch will open when it detects about 400psi in the A/C system. I think its mounted to the back of the compressor, and it IS wired in seris with the low pressure switch.

and you are sure you have the correct amount of charge in the car?

 

maybe koolaid kid will jump in on this one he knows alot about these systems

 

every a/c system is pretty much the same, just have **** in different spots

 

-Same guy as origianal poster I was on buddy's PC-

Pretty sure, It's got 32 Oz of r134a. it Blows pretty cold when I jump the relay.

When I jUmp the relay the High pressure side climbs to about 250-260 (Or it did last night, which is about the 3x ambiant temp rule of thumb I always heard)

Also no parts store has a listing for a High pressure switch for this car.
(Kragen or Monument)
-and I don't remember any switch on the back of the compressor, Just a single connector I assumed it was for the clutch.

Can I replace the low pressure switch without discharing the system? I'm pretty sure it has a schrader valve.

Thanks

 

One more thing. I tested across the pins on the switch with an ohm meter. I got something like 2KOhms. (across any 2 of the 3 pins)

thanks

 

I have the same problem, did you find out what it was?

 

Dude, this is a 3 year old thread you've dredged up.

 

I know it was the only thing that i could find that Matched my problem to the T. someone mite know the answer?