Okay...I am having some issues with overheating. And A/C.

The compressor clutch is disengaging and re-engaging. At highway speeds, I can notice the air go from back and forth from cool to hot. And shortly after, the engine temperature rises, but it returns to normal once I turn the A/C off.

At idle, at stoplights, I've noticed the clutch engaging and disengaging over and over. The compressor, clutch, and A/C fan assembly are all new. With the compressor and low pressure switch just being replaced over the weekend.

Any suggestions?

 

The compressor engaging and disengaging is normal operation.

 

I know that's normal, but not as frequently as it was doing. I'm riding in freeway traffic and I can feel the air get cool then switch back and get warm and then switch back and get cool over and over again. Then when I got to a stop light sitting still it kept coming on and off again blipping my idle up and down. Continuously engaging in re-engaging. Not just occasionally

 

Hmm. I would try getting a refrigerant refill. It just might have gotten low over the years and just needs a bit more pressure. Cheap and easy and might fix your problem.

 

If you have a radiator / cooling problem and your engine temp gets too hot it will shut your AC off. If you have a OBD scanner you can watch the actual temps that it is getting to before AC shut down. If you have a advanced scanner it may monitor the refrigerant pressure too.

 

This is my guess. The compressor will cycle oddly when the charge is low. I'm guessing these have a built in protection circuit that prevents short cycling, which will happen with a low charge, to prevent damage to the compressor. Basically it will control the duty cycle to prevent it from re-engaging for a certain amount of time after dis-engaging, which would explain why you feel the air warm up (not enough refrigerant to flow and not enough time has passed to allow the compressor to re-engage).

 

From my reading of the shop manual, a bad pressure sensor may be the culprit. It's atop
the AC fluid reservoir on the passenger side of the radiator.

Dan

 

You can easily troubleshoot nearly any AC problem by simply hooking up the manifold gauges and watching them.