A method of controlling the loading and unloading of a scroll compressor includes selectively loading and unloading a scroll compressor by engaging and disengaging, respectively, compressor members with the controller in response to system load data, monitoring at least one of the discharge pressure and the suction pressure at a predetermined time interval for a continuous time period, storing values based on the at least one of the discharge pressure and the suction pressure during the continuous time period, and determining a predetermined value indicative of compressor operation in which the compressor members are engaged. The method further includes comparing at least one of the stored values with the predetermined value and providing a signal to cease operation of the compressor when the comparison fails to indicate compressor operation in which the compressor members are engaged.