In a refrigeration system, foaming of the crankcase oil may cause the （）.

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• To correct the condition of slugging and flooding back in a refrigeration system, it may be necessary to （）.

  A . re-adjust the discharge pressure B . clean the expansion valve screen C . add refrigerant D . adjust the expansion valve

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• A liquid indicator sight glass is useful in determining whether or not a refrigeration system is sufficiently chargedIt is generally located in the（）.

  A . high pressure liquid line B . low pressure liquid line C . high pressure vapor line D . low pressure vapor line

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• The receiver used in a refrigeration system（）

  A . stores liquid refrigerant B . collects non-condensable gases C . allows refrigerant sub-cooling D . prevents compressor surging

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• 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

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• In a refrigeration system, if the cooling water to the condenser fails, the（）.

  A . box temperature solenoid valve will close B . expansion valve will close C . compressor will shutdown D . king valve will ope

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• 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 gla

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• One cause of high head pressure occurring in a refrigeration system can be （）.

  A . insufficient cooling water flow to the condenser B . a low refrigerant charge in the system C . the liquid valve is open too much D . high evaporator superheat

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• In a refrigeration system, the refrigerant absorbs the latent heat of vaporization in the（）.

  A . compressor B . condenser C . receiver D . evaporator

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• The effect of high vapor superheat in a refrigeration system, is a/an （）.

  A . increased capacity of the compressor B . more efficient operation of the thermal expansion valve C . decreased capacity of the compressor D . loss of receiver capacity

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• Crankcase sweating in a refrigeration system is caused by （）.

  A . a stuck solenoid valve B . a shortage of refrigerant C . too much oil in circulation D . too much superheat

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• Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）

  A . Sub-cooled liquid B . Sub-cooled vapor C . Superheated vapor D . Liquid

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• A liquid sight flow indicator in a refrigeration system is examined and gas bubbles are noted in motion with the fluid flowThis means （）.

  A . the system is fully charged B . there is air leaking in from the condenser C . ice crystals are forming in the refrigerant D . the system contains less than a full charge of refrigerant

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• The presence of bubbles in a refrigeration system liquid line may （）.

  A . promote refrigerant dehydration B . be absorbed in the receiver C . cause low condensing pressure D . carry moisture and lead to corrosio

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• The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as the （）.

  A . condenser B . vapor generator C . accumulator D . evaporator

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• 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

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• An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.

  A . restriction in refrigerant piping B . air and non-condensable gases in the condenser C . water in the refrigerant D . flooding back of liquid refrigerant from the evaporator

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• In an operating refrigeration system low on refrigerant, a liquid line sight glass will（）

  A . be clear B . be blue C . be light green D . show bubble

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• The latent heat of evaporation is dissipated in the （） in a compression refrigeration system.

  A . evaporator B . condenser C . expansion valve D . compressor

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• A solenoid valve used in a refrigeration system should be installed （）.

  A . with the axis of the solenoid horizontal, sensing temperature of the box, and upstream of the thermal expansion valve B . upright, sensing temperature of the box, and upstream of the thermal expansion valve C . upright, sensing temperature of the box, and downstream of the thermal expansion valve D . upright, sensing heat of the tail coil, and upstream of the thermal expansion valve

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• The function of （） in a refrigeration plant using Freon is to move moisture from all refrigeration system.

  A . filter B . filter drier C . heat exchanger D . air cooler

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• If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is （）.

  A . too much refrigerant in the system B . oil entrained in the refrigerant C . less than a full charge of refrigerant in the system D . ice crystals forming in the refrigerant

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• A pressure drop in the liquid line of a refrigeration system may cause（）

  A . the solenoid valve to seize B . the compressor to hunt C . flash gas to form in the liquid line D . the expansion valve to freeze ope

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• 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

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• The pressure range between the system cut in and cut out pressures in a refrigeration unit is known as_______.

  A.opposing operational drag B.pressure distribution C.differential D.system purge

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