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Steve, Service Manager
Category: Chevy
Satisfied Customers: 5494
Experience:  25+ Years experience as a professional working automotive technician; ASE L1 master technician
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1992 corvette: I changed relays, and fuses..high pressure..hood

Resolved Question:

I have a 1992 corvette ,the problem I'm having is that a/c compressor doesn't come on, the system is charged,the switch in the car comes on, I changed relays, and fuses and everything is fine,as far as I know.I dont have power on the low pressure cutoff switch or on the high pressure cutoff.Is there any other switch or under the hood that will make the compressor come.I'm stumped.
Thanks a lot arnold
Submitted: 10 years ago.
Category: Chevy
Expert:  Steve replied 10 years ago.


Do you mean there is not power at either wire of the low pressure switch, or that there is power at one side but it is not passing through the switch?

Customer: replied 10 years ago.
Hi steve: there is no power from the wires at all on either side on the low pressure switch
Customer: replied 10 years ago.
Hi Steve:There is no power on the plug that goes into the low pressure That means the two wires are dead Thanks Arnie
Customer: replied 10 years ago.
Relist: No answer yet.
Expert:  Steve replied 10 years ago.


Assuming this is the manual A/C system, the low pressure (clutch cycling) switch on the accumulator receives power from the engine control module on the green wire; the dark blue wire is the ground side of the circuit, and runs to the control assembly.

If there is no power on the green wire, then it is because the ECM has not commanded compressor operation.

The first thing to do to diagnose this type of fault is to connect a scan tool capable of displaying live engine data, and see what the scan tool displays as A/C system pressure. This will tell you whether to look at the control side of the system (ECM, switches, wiring) or the refrigeration/ pressure transducer side of the system for the source of the problem...

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