It depends on what kind of compressor you have on whether or not the compressor runs all of the time or cycles. I believe the compressors on our cars do not cycle. You can still be low on refrigerant and the compressor still come on but it can get to the point that its way too low and the system will shut the compressor down so it doesn't get ruined.

You need to put a set of gauges on it and see what your low and high pressures are which can determine if you are low.

Wayne

 

Actually I think they do cycle. I know that on mine, the compressor must be shutting off because it gets too cold. It was recently topped off and shuts off when the temp. gauges read 32-34 degrees F. Also, the temp. gauges fog up when it's off.. This is the compressor for the 3.4 though. The 3.8 might have the same one, but I'm not sure on that, though.

 

The compressor will shut off if something in the system is not right to protect the compressor but that does not mean its a cycling compressor. I will have to find out for sure.

Wayne