Question 66Refrigeration & AC - 1st Asst/Chief

70% to pass

When pumping down an air conditioning system to test the low-pressure cutout switch, assuming that the compressor is running, what should be done to initiate the test?

Astop the compressor
Bsecure the condenser
Cclose the "king" valve
Dstop the circulating pump
AI Explanation

The correct answer is C) close the "king" valve. To test the low-pressure cutout switch in an air conditioning system, you need to gradually reduce the pressure in the system. Closing the "king" valve, which is the main refrigerant service valve, will isolate the compressor and allow the pressure to drop, triggering the low-pressure cutout switch. This is the proper method to initiate the test without stopping the compressor or other components. The other options are incorrect because stopping the compressor (A), securing the condenser (B), or stopping the circulating pump (D) would not properly test the low-pressure cutout switch by gradually reducing the system pressure.

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Official Resources
46 CFR Machinery & Electrical 46 CFR Engineering USCG National Maritime Center
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