A/C compressor wont kick on

[mario65]

Car still has R12. I had a shop do a quick look and they said it has plenty of freon. They sent 12 volts to the compressor and it kicked on fine. I have a flashing A/C light when I first crank it. I checked for A/C codes and there arent any. Is there a relay anywhere or something simple I should check?



thanks

[tpr60]

Had a buddies A/c do the same thing, chased the wiring and problem for a whole day. End up replacing the dash a/c controller with a used one out of a 90 L98, everything worked perfect. The factory wiring chart didn't seem to match how the car was built. Hope this helps.

[VetteMed]

Little concerned about the "has plenty of freon" comment, as without evacuating and weighing the refrigerant, that is a conclusion that really can't be made.

Measuring high and low side pressures while the compressor is running, can give some idea of the state of charge, but is not really a way to be sure there's a full charge.

To see if a low charge is what is causing the compressor to fail to kick on, the low pressure cutoff switch terminals can be jumped. this is the switch in the low-pressure (suction) line, as it leaves the evaporator core. Unplug it, jump the terminals on the plug of the harness, and see if the compressor kicks on. If it does, it's either a bad switch or a low charge secondary to a leak.

[mario65]

Originally Posted by VetteMed

Little concerned about the "has plenty of freon" comment, as without evacuating and weighing the refrigerant, that is a conclusion that really can't be made.

Measuring high and low side pressures while the compressor is running, can give some idea of the state of charge, but is not really a way to be sure there's a full charge.

To see if a low charge is what is causing the compressor to fail to kick on, the low pressure cutoff switch terminals can be jumped. this is the switch in the low-pressure (suction) line, as it leaves the evaporator core. Unplug it, jump the terminals on the plug of the harness, and see if the compressor kicks on. If it does, it's either a bad switch or a low charge secondary to a leak.

Thanks I believe its low on freon even though the guy I took it to first said it wasn't. I am going somewhere else tomorrow. I hate taking it and leaving it. I wish I knew someone I could trust with it.

[petefias]

Originally Posted by VetteMed

Little concerned about the "has plenty of freon" comment, as without evacuating and weighing the refrigerant, that is a conclusion that really can't be made.

Measuring high and low side pressures while the compressor is running, can give some idea of the state of charge, but is not really a way to be sure there's a full charge.

To see if a low charge is what is causing the compressor to fail to kick on, the low pressure cutoff switch terminals can be jumped. this is the switch in the low-pressure (suction) line, as it leaves the evaporator core. Unplug it, jump the terminals on the plug of the harness, and see if the compressor kicks on. If it does, it's either a bad switch or a low charge secondary to a leak.

Spot on. That's exactly what I had to do.

[mario65]

Well the first guy I took it to was either a newb or was trying to make some money. The car had slow leaked the R12 out enough to cause the clutch to not kick on. I had a another shop check it. Filled it and problem solved

You guys were right

thanks

[VetteMed]

Glad to hear you got the problem identified properly!