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?

Correct Answer: Option C — close the ‘king’ valve

Closing the liquid line king valve traps refrigerant in the condenser and receiver while the running compressor pumps the low-pressure side down. This action triggers the low-pressure cutout switch to verify proper electrical and pneumatic safety shut-down functionality.