1992 A/C compresser constantly on
Thread Starter
5th Gear
Joined: Nov 2008
Posts: 5
Likes: 0
1992 A/C compresser constantly on
I recently purchased a nice low-mileage 1992 convertible. The only thing I can find wrong with it is the A/C compressar runs continuously even with the climate control switch in the off position. It also runs in the auto setting even with the inside temp settings set high enough that it shouldn't come on. The car has the automatic climate control option. This is my first Vette and I am new to this forum. Does anyone out there have any ideas on what I should look for or what the problem might be? Thanks!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
The Auto position always engages the compressor. Whether or not it engages is a function of the pressure of the gas flowing through the lines (which has a temperature), but not the desired air temp you've selected at the Controls. Your Owner's Manual will outline it in detail.
Compressor shouldn't engage with the Controls set to Off. Signal is from the Dash over a serial data line to the Processor (called a Programmer), and onto the PCM which drives (grounds) the Compressor Clutch Relay. If you have a scanner, hook it up and see if the PCM is seeing an a/c request with the Controls set to Off. If so, the Controls or the Programmer are usually the culprit and removing the Programmer fuse will rule out the PCM if the clutch then disengages. Absent a scanner, some possibility that the Relay is shorted to ground or the wiring from the Compressor to the Relay is grounded somewhere. That wiring runs from the compressor through the Low Pressure Switch harness (mounted on the Evaporator outlet) so you might check around there if the Relay is ok.
Compressor shouldn't engage with the Controls set to Off. Signal is from the Dash over a serial data line to the Processor (called a Programmer), and onto the PCM which drives (grounds) the Compressor Clutch Relay. If you have a scanner, hook it up and see if the PCM is seeing an a/c request with the Controls set to Off. If so, the Controls or the Programmer are usually the culprit and removing the Programmer fuse will rule out the PCM if the clutch then disengages. Absent a scanner, some possibility that the Relay is shorted to ground or the wiring from the Compressor to the Relay is grounded somewhere. That wiring runs from the compressor through the Low Pressure Switch harness (mounted on the Evaporator outlet) so you might check around there if the Relay is ok.
