单项选择题
The purpose of the purge valve at the top of the condenser in a refrigerating system is to（）
A.remove any air that may accumulate in the system B.take out unpleasant fumes from the refrigerant C.vent off excess refrigerant in an emergency D.permit opening the refrigerating system for cleaning and inspecting
单项选择题 What is the purpose of sub cooling R-12 in the condenser?（）
单项选择题 In terms of pressure and temperature in the refrigerant in the compressor, what happens to the primary?（）
单项选择题 The solenoid valve can be typed as a（）
