Compressor plugged in for 24 hours prior to running

In the training module a a/c system should not be tested if it has not had power 24 hours prior. Why is this not true for refrigerators, roof top a/c units on RV’s etc.

This is related to units equipped with a crankcase heater. These units should be left powered for 24 hours before they are started. Look up the purpose of a crankcase heater. Usually you’ll find them on heat pumps.