单选题A pressure drop through the refrigerant liquid line may cause （）.A solenoid valve to seizeB compressor to huntC formation of flash gas in the liquid lineD expansion valve to freeze open

To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the_______ .

A.suction service valve as a vapor

B.suction service valve as a liquid

C.discharge service valve as a vapor

D.charging valve as a liquid

In a chilled(冷的) water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by ______.

A.increasing refrigerant pressure in the coil

B.increasing chilled water flow through the cooler

C.sub-cooling the refrigerant in the condenser

D.superheating the refrigerant in the compressor

If the refrigeration compressor crankcase is sweating, the cause may be due to

A.a shortage of refrigerant

B.the compressor running continuously

C.liquid refrigerant returning to the compressor

D.the compressor short cycling on the high pressure cutout

If the superheat value of a thermostatic expansion valve is set too low, the _.

A.the suction line will be abnormally cold and liquid may slug back to the compressor

B.the suction line will be hot due to a reduced amount of refrigerant returning to the compressor

C.the temperature of the refrigerant within the condenser will remain the same

D.the temperature of the refrigerant passing through the sub-cooler will decrease

The temperature of the refrigerant in the evaporator coil depends mostly upon the ___.

A.refrigerant pressure in the evaporator

B.cooling water temperature to the condenser

C.heat load in the refrigerator compartment

D.solenoid valve in the liquid line