ESCO Commercial Refrigeration Practice Test

These questions are part of the practice quiz. Start practicing

• When the defrost cycle is terminated, the evaporator fans will?
• Which step should you take after verifying safety and power in troubleshooting a refrigeration system?
• Which national code governs electrical installations in the United States?
• During maintenance, what is the recommended position of the compressor service valves to reduce the risk of leakage?
• If five frozen food cases iced up on a single compressor, what is the most likely fault?
• In a vending machine with a capillary metering device, after replacing the filter dryer and evacuating, the system shows low suction and head pressures with low motor amps. Which could be the cause?
• In a system with several evaporators at different temperatures, which valve arrangement allows them to share one compressor?
• What does HACCP stand for and why is it relevant to commercial refrigeration?
• What is the function of the evaporator pressure regulator valve?
• In low temperature refrigeration applications (excluding ice makers), box temperatures normally fall within which range?
• If an oil separator is not used, what should be installed in every vapor carrying line?
• Superheat measurements are best taken
• An ice machine auger makes a loud noise and the overload trips after resetting; the motor is very hot. The indicated cause is the lack of water flow. What is the correct explanation?
• Why is it important to know the refrigerant type when servicing a system?
• Which cooling system component's performance is significantly affected by low ambient temperatures?
• Which refrigerant line is most sensitive to improper sizing?
• After completing service work on a refrigerator, the compressor service valves should be in which position?
• Which sequence of actions occurs in a properly functioning condenser?
• Blended refrigerants should be charged into a running system
• How does a thermostatic expansion valve regulate refrigerant flow?
• Capacity control of a large compressor can be performed with?
• Which term describes capturing refrigerant in the condenser and/or liquid receiver during operation?
• Which temperature marks the onset of ice production in an icemaker?
• In an air-cooled condenser, the refrigerant temperature is typically higher than ambient air by about how many degrees Fahrenheit?
• Which PPE should be used when handling refrigerants or brazing?
• Defrosting a low temperature evaporator can be accomplished by
• What valve is used to connect multiple evaporators of different temperatures to a single compressor?
• How is defrost termination typically determined?
• Why is nitrogen purge commonly used when evacuating lines?
• A TXV with an external equalizer is typically used on evaporators with what characteristic?
• What is the recommended next step after implementing corrective actions in a malfunctioning refrigeration system?
• Name three common compressor types used in commercial refrigeration.
• How is pressure–temperature data used when charging a system?
• What is a zeotropic blend, and how does it affect system charging and cycle behavior?
• In capillary tube systems that use suction line heat exchangers, when should the superheat reading be taken?
• Which action best helps determine whether a refrigerant system is correctly charged relative to its nameplate?
• Which component primarily regulates refrigerant flow to the evaporator?
• Which compressor type allows access to its internal components for servicing?
• Excessive frost on the evaporator causes which result?
• Which defrost cycle uses hot gas to melt frost and can be initiated by a timer?
• A ______ is usually required for ultra low temperature applications.
• Medium temperature refrigeration applications will normally provide box temperatures of
• Short cycling in a pumpdown system is most likely caused by a leaking which component?
• Why is inert nitrogen purging used during brazing?
• In flooded evaporator setups, a _____ type device is used to maintain the liquid level.
• Esther-based oils are considered what type?
• Cooling towers that pass air over water to remove system heat are limited in capacity by
• Starting at the compressor discharge, what is the next component in the basic cycle?
• A sequence of five frozen food cases operated by one compressor results in all five cases iced up. What is the likely problem?
• Evaporator superheat is defined as the difference between the refrigerant's boiling temperature inside the evaporator and the temperature at the evaporator outlet.
• What is the major difference between a cooling tower and an evaporative condenser?
• To achieve peak efficiency and performance in a capillary tube system, the system must be
• A severe evaporator freeze up may cause which condition?
• After replacing the filter dryer, the system is evacuated. Why is it important to remove air and moisture from the system?
• Low temperature refrigeration applications, other than ice makers, normally provide box temperatures of which range?
• The effect of an inefficient water cooled condenser will
• What are typical applications for R-404A and R-134a in commercial refrigeration?
• What time interval is required between each superheat adjustment?
• A hot gas defrost cycle can be initiated by a?
• To achieve a 15 psig cut-out when the cut-in is 40 psig, what differential setting is required?
• Why is heat rejection to ambient necessary in the refrigeration cycle?
• What does EPA Section 608 regulate for technicians?
• In a supermarket with a rooftop condenser, five low-pressure controls open and the liquid receiver is full, with the hot gas discharge line cold. What is the most likely cause?
• Why should an oil separator be kept warm in refrigeration equipment?
• Which device limits evaporator pressure to a predefined minimum value in some systems?
• The term refrigerant conditions refers to which states?
• Which method is NOT typically used to locate leaks in a charged system?
• For accurate evaporator superheat measurements on long suction lines, the pressure is read at which component?
• What action should be performed first when a refrigeration system won't restart after a lockout?
• Which statement about refrigerant oil is correct?
• Explain electric defrost and hot-gas defrost methods.
• On a multi circuit evaporator, if one circuit has a higher superheat than the others, this could be caused by
• What is the primary reason to clean condenser coils?
• In a water-cooled condenser, the condensing temperature is typically about how many degrees Fahrenheit higher than the leaving water?
• What type of oil is used with HFC refrigerants?
• In a system with a capillary metering device, what effect does using a larger filter dryer have on startup current draw?
• If a walk-in cooler requires a high percentage of moisture in the air due to the product being stored, the logical evaporator TD would be
• Water cooling towers require a periodic blow down to control
• Which safety precautions are essential during brazing or soldering copper refrigerant piping?
• A system using an automatic expansion valve (AEV) is not cooling and runs continuously. The gauges reveal low head pressure, but the suction pressure is acceptable. This could be caused by
• What is the proper procedure for cleaning condenser coils and why?
• High temperature refrigeration applications typically provide box temperatures in which range?
• A dirty evaporator and subsequent low evaporator pressures will cause
• In a dry type evaporator, achieving boil-off near the end of the coil improves which aspect?
• To adjust a water cooled condenser for design condensing temperature, you would:
• Why is proper ventilation important when brazing refrigerant system joints?
• Vibration eliminators should be installed _______ to the compressor crankshaft centerline.
• The refrigerant condensing temperature in a water cooled condenser is normally about _____ higher than the leaving water.
• The oil separator is installed in which line?
• What vacuum level is typically required to evacuate a refrigeration system before charging?
• Which component maintains superheat in the evaporator?
• Which of the following can serve as metering devices in a basic vapor-compression cycle?
• What is the purpose of a refrigerant recovery machine?
• Which instrument is used to verify refrigerant pressure on the low side?
• In the vapor-compression cycle, what is the correct sequence from compressor discharge to return?
• Superheat is the temperature rise of refrigerant vapor above its saturated temperature at the suction pressure; what is its primary purpose?
• What is the purpose of oil traps in vapor lines?
• The suction accumulator prevents flood back from which condition?
• Describe a systematic approach to troubleshooting a malfunctioning refrigeration system.
• Multiple compressors provide
• The refrigerant and an air cooled condenser will normally contends at approximately _____ higher temperature than the air passing over it.
• If an oil separator is not used, what should be installed in all vapor carrying lines?
• Why is suction line insulation important?
• In a low-ice-production cube ice machine, with a harvest solenoid and a thermostatic expansion valve, and a water reservoir at 32°F, the harvest solenoid shows a temperature rise of about 10°F and suction is slightly elevated. What is the faulty component?
• Automatic pump down systems are used to prevent which condition?
• Which statement best describes how defrost termination is typically determined?
• Which tool is used to verify parallel misalignment between a motor and its coupling?
• What is the purpose of refrigerant recovery equipment?
• Which two terms describe the manually adjustable settings on a high-pressure switch?
• What symptoms indicate a malfunctioning condenser fan motor?
• In a five-compressor rack where all low-pressure controls are open, which fault is most consistent with the observed symptoms?
• Which indicators suggest a system may be undercharged?
• What term describes a thermostatic expansion valve that creates an unstable suction pressure?
• Which of the following determines the viscosity of refrigeration oils used in refrigeration systems?
• Which four components form the basic vapor-compression refrigeration cycle?
• At what evaporative temperature does an icemaker begin to make ice?
• What is a common method to defrost a low-temperature evaporator?
• A water regulating valve used to control water flow in a water cooled condenser application can be most accurately adjusted by
• What is a key safety precaution when handling refrigerants to avoid injury?
• What is the role of oil in a refrigeration system, and what happens if oil returns poorly?
• What issue is indicated by moisture under the flare nut causing a slow refrigerant leak after repeated freezing and thawing?
• What is the normal operating position for a compressor service valve?
• What is the purpose of a low-pressure switch in a refrigeration system?
• Which statement best describes the purpose of lockout/tagout procedures in service work?
• Which statement best describes the behavior of zeotropic blends during evaporation and condensation?
• A refrigeration system that uses the evaporator of the first stage to exchange heat with the condenser of the second stage refrigeration system is called a
• In a typical system, where is the oil separator located?
• An evaporator pressure regulator valve (EPR valve) is a mechanical control that
• Dry type evaporators operate most efficiently with a superheat setting of approximately
• Liquid slugging of the compressor can be caused by which condition?
• What device is used to check for parallel misalignment of a motor coupling?
• The difference between the refrigerant's boiling temperature inside the evaporator and the evaporator outlet temperature is known as
• Which pressures are used by an oil pressure differential switch to operate its time delay heater?
• Which system is usually required for ultra low temperature applications?
• What symptom is commonly associated with TXV hunting?
• What instrument is typically used to measure the vacuum level in microns during system evacuation?
• When retrofitting a CFC/mineral oil system to an HFC-based refrigerant, what is required?
• Which instrument is commonly used to measure low-side refrigerant pressure in the field?
• What is the purpose of an oil separator?
• The two manually adjust the parameters of a high-pressure switch are
• Cryogenics refers to refrigeration systems operating at what temperature range?
• Why is evaporator coil airflow critical for performance?
• When the compressor service valve is back seated, which port closes?
• The type of compressor that allows access to the internal components is the
• In a refrigeration control circuit, what is the function of a contactor?
• The relationship between low side absolute pressure and high side absolute pressure is called?
• Some special applications use a flooded evaporator (operated full of refrigerant) to maintain the proper level of liquid refrigerant. What type of device is used?
• How should blended refrigerants be charged into a system?
• On an expansion valve refrigeration system, a low pressure control can indirectly be used for what purpose?
• Which tool is commonly used to locate leaks in a charged refrigeration system?
• If liquid refrigerant accumulates in the oil separator and returns to the crankcase with the oil, what is the result?
• An expansion device that is stuck open will cause
• An automatic pumpdown system requires a
• In a dry type evaporator, where must liquid refrigerant boil off to maximize efficiency?
• Name two common strategies to improve energy efficiency in commercial refrigeration.
• Which statement about condenser types is true?
• Head pressure control valves permit hot gas to travel directly to which component?
• Which component is designed to prevent refrigerant migration to the crankcase during the off cycle?
• What device protects the high-pressure side from excessive pressure?
• What is a key limitation of the sight glass in modern systems?
• Capillary vs TXV: Compare a capillary tube to a TXV in terms of control and efficiency.
• On a rack of multiple compressors, which device controls each individual compressor?
• For walk-in coolers needing a high moisture content, the typical evaporator TD is
• Which code should be followed for electrical installations in the United States?
• Subcooling is the liquid refrigerant temperature below its condenser saturation temperature; what is one benefit of higher subcooling?
• How is a defrost cycle typically terminated in most reach-in refrigerators?
• Expendable refrigerant means
• Which is a common sign of a refrigerant leak?
• What is a sight glass and what are its limitations?
• Medium temperature refrigeration applications will normally provide box temperatures of which range?
• In a parallel compressor rack system, which header is typically common to all compressors?
• What is the typical supply voltage for many commercial refrigeration systems in the U.S.?
• If an accumulator is holding liquid refrigerant, what effect does this have on system operation?
• Which observation most strongly supports that an evaporator is starved for refrigerant?
• The symptoms described include the compressor shutting off on the oil pressure switch, the oil sightglass being half full, and suction pressure at 3 psig. What is the most likely cause?
• In a TXV system, which two measurements does the valve respond to?
• The crankcase heater is used to prevent what during the off cycle?
• A walk-in freezer cycles on and off with an accumulator in the liquid line and ice forming from the liquid line solenoid to the expansion valve. The low-pressure switch closes prematurely. What is causing this condition?
• What is the function of a condenser fan motor?
• Walk-in cooler investigation shows ice on the evaporator, evaporator superheat of 22°, suction and discharge pressures are low, and condenser subcooling is 2°. What is the most likely issue?
• Why is system cleanliness important during maintenance?
• Workable head pressure during periods of low ambient temperature can be achieved by using
• What valve is used to control excessive pressure entering the compressor during a hot pull down?
• A low temperature evaporator used for cooling space or product refrigeration should be defrosted periodically. Which option completes the statement?
• Dry type evaporators operate most efficiently with superheat in which range?
• A TXV with an external equalizer is used on
• When measuring oil pressure on the compressor with a pressurized oiling system, how is actual oil pressure determined?
• Which component is often placed in the suction line to help prevent flood back into the compressor after hot gas termination?
• Low ambient temperatures seriously affect which type of units?
• What should you do if a system won't restart after a lockout?
• During a defrost, moisture was found under the flare nut on the evaporator side of the expansion valve, leading to a slow refrigerant leak after repeated freezing and thawing. What was the root cause?
• An off-cycle defrost method is often used on evaporators operating at a minimum of what temperature?
• What pH level is considered neutral and desirable for ice machine or cooling tower applications?
• What valve is used to prevent evaporator pressure from falling below a set limit?
• Which of the following is NOT a metering device in a basic vapor-compression cycle?
• The 'low ambient control' is used to control which parameter?
• A properly functioning condenser will first de-superheat, then sub-cool. Which option best describes this sequence?
• After a defrost cycle ends, the evaporator fans will
• In a parallel compressor rack system, what header is typically shared?
• If a system has a long suction line riser, an oil trap should be installed every how many feet of vertical rise?
• Why must refrigerants be handled as hazardous materials and what precautions apply?
• To control scaling in cooling towers, operators perform periodic what?
• Why do suction line filter dryers have two service ports?
• An oil pressure differential switch utilizes which pressures in opening the time delay heater?
• Name two main condenser types used in commercial refrigeration.
• Esther-based oils are which type?
• An evaporator used to chill liquids is operating within normal superheat setting, but the system is not cooling the product properly. What is most likely the cause?
• Too low superheat increases the risk of what?
• The oil return orifice inside a suction line accumulator is designed to
• Which component is specifically designed to meter the return of liquid refrigerant and oil to the compressor?
• When measuring evaporator superheat on a long suction line, the pressure reading should be taken at the
• What factors lead to evaporator frost buildup?
• "Pump down" means to capture system refrigerant in the
• A custom reach-in freezer had a burned-out compressor replaced; evaporator seemed starved for refrigerant; liquid line was sweating after a filter dryer replacement. What is the most likely cause?
• The thermostatic expansion valve maintains what in the evaporator?
• Cooling towers that pass air over water to remove system heat are limited in capacity by which factor?
• Bubbles or foaming in the compressor's oil sight glass are an indication of which condition?
• Which device senses superheat to control refrigerant flow in the evaporator?
• What is the effect of insufficient heat rejection on the refrigeration cycle?
• What is the primary function of a condenser in the refrigeration cycle?
• What is the function of a thermostat or digital controller in a display case?