单项选择题If the temperature in the icebox is too high, the trouble could be()

A.a clogged scale trap
B.air in the system
C.automatic controls not functioning properly
D.insufficient cooling water to the condenser


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1.单项选择题Air or noncondensable gas is removed from a refrigeration system by a ()

A.separating chamber
B.system of baffles
C.purge valve
D.vacuum reducing valve

2.单项选择题Where are the zinc plates located?()

A.saltwater side of the condenser
B.refrigerant side of the condenser
C.in the evaporator coils
D.in the suction strainer

3.单项选择题The device used for low-pressure control and high-pressure cutout on a compressor is called a()

A.cutout
B.pressure controller
C.controller switch
D.cutout switch

4.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

5.单项选择题What is the purpose of sub cooling R-12 in the condenser?()

A.to increase the system efficiency by sensible heat transfer
B.to stop the liquid from flashing
C.to reduce the load on the compressor
D.to remove latent heat of vaporization and the suction piping transfer

6.单项选择题In terms of pressure and temperature in the refrigerant in the compressor, what happens to the primary?()

A.its pressure and temperature are both lowered
B.its pressure and temperature are both raised
C.its pressure is lowered and its temperature is raised
D.its pressure is raised and its temperature is lowered

7.单项选择题The solenoid valve can be typed as a()

A.thermal valve
B.magnetic stop valve
C.bellows valve
D.bimetallic valve

8.单项选择题If the compressor runs continually, the cause might be the()

A.high-pressure cutout switch is jammed open
B.low-pressure switch is jammed shut
C.thermal bulb is not operating properly
D.scale trap is clogged

9.单项选择题The bulb for the thermal expansion valve is located()

A.in the middle of evaporator coils
B.near the evaporator coil outlet
C.near the evaporator coil inlet
D.on the bottom row of evaporator coils

10.单项选择题The thermal expansion valve responds to the()

A.amount of superheat in the vapor leaving the coil
B.amount of superheat in the liquid
C.temperature in the evaporator coils
D.pressure in the evaporator coils