Icemann185

So I have an 02 GT that has had a motor built from ground up. But having problems with my AC because the clutch is not cycling like it should. But ran some test and found that the PCM is not sending a ground to the relay. So I am at the point of what tells the PCM to send a ground to the relay? Thanks for all the help in advance.

dawson1112

I dont think the PCM has any thing to do with the AC. But the CCRM ( constant control relay module ). Also if the AC compressor clutch is cycling on and off it is because the refrigerant level is low. If it is not coming on at all and you know the system is full, there is a chance it is the low pressure control switch.

Icemann185

I changed the low pressure switch and the ccrm. That the clutch will engage at the first turn on the system and run for about 2 to 3 mins the shut off and not come back on the engine rpms will cycle up and down like the clutch is engaging but it is not.

Derf00

Do you have a set of manifold gauges to see what the a/c system is doing?

Icemann185

Yea put gauges on it and reads right no problems there. Just been stumped with how it is doing

Derf00

If readings are normal when it's on/ff for the high/low side then yep, you're back to an electrical gremlin. Normally, the low pressure switch just cuts he power to the relay if/when the low side is too low. Check its harness and trace the wires to make sure it A) has continuity and B) has voltages when required. Do the same for the AC Compressor clutch connector.

It is also possible the AC relay is worn. When that happens the relay won't stay energized when it overheats and it will open the circuit (cutting power). Once it cools off it closes the circuit again. Maybe find a relay in the fuse area that is the same type and swap it temporarily.

WhiteFoxGT

could be excessive air gap at the compressor clutch. over time they wear the material and that field coil is only so strong. when it stops "working" take a long metal something and ( CAREFULLY) see if the clutch is magnetized even if the compressor isnt spinning anymore. The system might be operating correctly minus the actual clutch being able to spin due to air gap.

fastbackford351

When my AC system was having a similar issue it was the relay. I replaced it and haven't given it another thought. Cheap and easy to try.

GT Nate

well, the clutch is that part with the three steel bars which expand out when turning. They are engaged by an electromagnet which sits in the ac compressor. I took mine out on my 93 Tbird and it was a bitch to get it back in. but I did it.

I noticed my ac was turning off and on far more than usual, so I bought some freon on eBay and put in in the system, problem solved. Cold air.

You could have a grounding problem ANYWHERE in the system as there's far more than one ground. Might do a check around see if any wires have corroded off where they used to be attached.

Good luck amigo!