单项选择题
In the refrigeration system, a shortage of refrigerant is indicated by （）.
A.the compressor short cycling on high pressure cut out switch B.high suction pressure C.high head pressure D.bubbles in the sight glass
单项选择题 Which of the following conditions must exist for heat to flow from one object to another?（）
单项选择题 A warmer than normal compressor suction line might be caused by （）.
单项选择题 The unloading system on an air compressor will （）.
