Question 39Refrigeration & AC - 1st Asst/Chief

The correct answer is A) The low pressure cut out switch. When you close the suction valve, the compressor loses its suction pressure. This causes the low pressure cut out switch to trip, preventing the compressor from starting. The low pressure cut out switch is a safety device that shuts down the compressor to prevent damage when the suction pressure drops too low. The other options are incorrect because: B) The high pressure cut out switch would only trip if the discharge pressure was too high. C) The lube oil differential pressure switch monitors the oil pressure, not the refrigerant pressure. D) The water regulating valve controls the condenser water flow, not the compressor operation.