Question 106Refrigeration & AC - QMED

The correct answer is A) short cycle on low-pressure cutout. With the evaporator coil accumulating excessive frost due to a failure of the defrost mechanism, the refrigerant flow through the evaporator will be restricted, causing the low-pressure side of the refrigeration system to drop below the low-pressure cutout setting. This will cause the compressor to short cycle on the low-pressure cutout, shutting the compressor off until the pressure rises back above the cutout setting. The other options are incorrect because: B) fail to start is not the likely symptom, as the compressor will attempt to start but be cut off by the low-pressure cutout; C) short cycle on high-pressure cutout is unlikely since the high pressure will not be the issue; and D) run continuously is incorrect, as the low-pressure cutout will prevent the compressor from running continuously.