Originally posted by mikemover
He means that the compressor is cycling on and off on its own...which is what it's supposed to do, progressively, as the refridgerant level gets lower and lower.
I believe the compressor will actually run MORE as the coolant level drops. When properly charged, the compressor cycles on and off - it's determined by the cooling needs...and to prevent freeze-up of the evaporator.
There is, however, a pressure switch which will shut down the compressor altogether if the coolant pressure (level) falls too low.