Moisture in a refrigeration system can cause （）.

Low compressor head pressure in a refrigeration system can be caused by ___.

A.insufficient condenser cooling water

B.excessive condenser cooling water

C.air in the refrigeration system

D.excessive refrigerant in the system

If the suction pressure at the refrigeration compressor is below normal, the cause can be

A.refrigerant overcharge

B.overfeeding by the expansion valve

C.a restricted suction strainer

D.due to short cycling of the compress

Ventilation ().

A、is a system for moving fresh air

B、can cut indoor pollution to a safe level

C、can cause some diseases

D、is better done through air-conditioning

Restrictions occurring in the small orifices(孔) of pneumatic control system components can be caused by ______.

A.moisture in the compressed air supply

B.excessive dryness in the compressed air supply

C.pressure surging in the compressed air receiver

D.insufficient lubrication of the system components

Some refrigeration systems have chemical moisture indicators installed in conjunction with the sight glass in the liquid line If excess moisture is present in the system, the indicator will

A.activate the driers

B.change color

C.secure the compressor

D.add a predetermined amount of liquid drier

An increase in the heat load to a refrigeration system will cause ______.

A.the suction pressure to decrease

B.the suction temperature to increase

C.increased ice formation on the evaporator coil

D.excessive short cycling of the compressor

Moisture is removed from a refrigeration system by

A.bleeding refrigerant from the condenser

B.opening a drain petcock on the oil separator

C.condensing the water in the heat exchanger

D.using a dehydrator cartridge

Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause______.

A.carbon deposits on the compressor suction valves

B.the evaporator temperature to increase

C.rapid corrosion of the thermal expansion valve

D.no operating problems