I have never noticed before but my AC pump engages and disengages about every 5 seconds.I can't hear it when I am driving but I idled it in the driving way cold and hot after driving and it constantly clicks on and off. Any thoughts?

 

Does your AC system seem to be performing normally on a hot day? If it is then the most likely cause is #2.

1) One cause can be a low charge. The systems have a pressure switch on the low pressure side of the compressor, if the charge is low the pressure will drop below the switch set point, when the compressor stops the pressure rises again and the cycle repeats. If this is the case you should have poor cooling performance.

2) Another cause is the evaporator temp sensor detecting to cold of evap temp.
This can occur if the blower fan speed is to slow or the air temp is cold. This is pretty typical in cool weather when running the system in defrost mode.

3) I do not know if this system has an over pressure sensor. Over pressure can be caused by a blockage in the system.

Hope this helps

jimb