Commercial Refrigeration II Practice Exam

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• How do evaporators in medium-temperature refrigeration cases normally defrost?
• Which refrigerant component prevents liquid refrigerant from returning to the compressor?
• Ultrasonic leak detectors locate refrigerant leaks by:
• Using heat-reclaim coils will help improve a building's overall:
• The correct way to discharge a capacitor is:
• Baseline condenser data focuses on inlet condition measured as?
• What is a common cause of overdefrost in a defrost cycle other than a refrigerant issue?
• Where in the system is an oil separator installed?
• Which device is designed to separate and collect some of the oil in the discharge line and return it to the compressor's crankcase?
• Why is the filter drier important?
• Which of the following is an example of baseline condenser data?
• What is meant by a system's baseline data?
• After diagnosing a defective compressor, the technician should:
• If the liquid oil acid test kit cannot be used, indicators may be connected to the
• Which systems use evaporator pressure regulators (EPR)?
• A flow control device that stops or allows the flow of a refrigerant in a refrigeration system based on an electric signal is called a
• Which component’s failure is listed as a possible cause of an iced-up evaporator in the given material?
• Why is it necessary to have controls for maintaining a minimum high-side pressure on outdoor air-cooled condensers?
• The contacts in a potential relay are typically in what state under normal operating conditions?
• What is the advantage of using a pressure relief valve to protect a receiver instead of a fusible plug?
• A safer alternative to debrazing components is to:
• Which type of valve is NOT considered an isolation valve?
• How can you tell when a filter drier is stopped up?
• How is a compressor's rated load amp rating, RLA, determined?
• Voltage drop across a switch indicates that:
• After reassembling the system
• Which valve type is typically used for on/off control but is not considered an isolation valve?
• When troubleshooting single-phase compressor motors, it is important that the technician:
• During normal defrost, the compressor is:
• If a restriction clears up when the system is turned off and allowed to warm, the restriction was probably due to:
• Which of the following is a potential cause of overfeeding the TEV?
• During troubleshooting, if the superheat value of the refrigerant leaving an evaporator is higher than normal:
• If an ohmmeter shows continuity but the resistance value is much lower than expected, this indicates:
• Moisture in the refrigeration system can also cause which of the following?
• After a compressor burnout cleanup, what is the key oil maintenance step?
• Electrical components can be categorized into two groups:
• What property of POE oil used with HFC refrigerants necessitates liquid-line filter driers?
• Which of the following is an example of baseline evaporator data?
• Suction line filters are generally designed
• When checking the resistance of the compressor start winding, a reading of OL on the multimeter indicates what?
• Why should the temperature inside the compressor be kept under 300°F?
• During a system cleanup, changing the oil in a hermetic compressor:
• How can a technician determine when a filter drier is stopped up and needs changing?
• Many technicians use a(n) ________ to measure all electrical characteristics.
• When replacing or repairing any electrical components, always verify that the:
• For new systems, when should baseline data be recorded?
• If suction superheat is lower than recommended, the most likely reason is:
• A reciprocating compressor with leaking valves will operate with:
• In most commercial refrigeration systems, where is the excess refrigerant that is not being used stored?
• Why should technicians be cautious when taking an oil sample from a semihermetic compressor?
• After a capacitor is discharged:
• What is a safer, non-brazing method for removing copper tubing connections when servicing equipment?
• An iced-up evaporator in a commercial freezer can be caused by which of the following?
• After a system cleanup the system should be charged:
• During troubleshooting, before documenting any of the system's pressures or temperatures it is best practice to:
• After flushing the lines and coils, the flush should be purged out using which gas?
• Why are liquid-line filter driers required for all systems using HFC refrigerant?
• Which of the following is an example of baseline condenser data used in energy efficiency assessments?
• To manually defrost a frozen evaporator coil, technicians should:
• During startup data collection for a condenser, which value is considered baseline?
• Which component is typically installed in the discharge line leaving the compressor to separate oil from the refrigerant?
• What type of systems normally use crankcase pressure regulators?
• What happens if you remove tubing before all the brazing material is molten?
• If the compressor oil on a hermetic compressor is acidic, the next step is to change the:
• What are the most common desiccant materials used in driers?
• Which parameter is used as a baseline data point for condensers?
• What breaks down to form poisonous gas in the presence of flames?
• Before opening the compressor crankcase to take an oil sample, you should
• What is the proper method for charging a system after cleanup according to the discussed guidelines?
• A discharge-line check valve primarily prevents which condition?
• Moisture indicators are normally part of which component?
• When checking the resistance of the compressor start winding, a multimeter shows 3.1 Ω. This indicates:
• If noncondensable gases are present in the system, which statement best describes the expected condenser pressure relative to the PT chart for the same refrigerant and temperature?
• After a system cleanup, the system's performance should be verified by ________ and recording key system operating performance specifications.
• What does a crankcase pressure regulator do?
• Which statement about a system's baseline data is true?
• Just before charging the system with clean refrigerant, you should
• Which trio of measurements is commonly used for electrical troubleshooting?
• Which component is designed to absorb moisture and contaminants from the refrigerant?
• How does an oil acid test kit indicate the presence of acid?
• What is the difference between a standard liquid line drier and a filter designed to be used following a flush procedure?
• Which instrument provides a visual indication of moisture condition in a refrigerant system?
• When reviewing condenser performance, baseline data should include which measurement?
• The inlet of the recovery pump should include?
• Which datum would be considered baseline when comparing condenser efficiency over time?
• In a baseline condenser data log, which value is recorded?
• Oil separators return oil to which location in the compressor system?
• The run winding on a compressor has a resistance of 0 Ω. This indicates that:
• The current relay coil is wired in which location in the circuit?
• A hot compressor with an infinite ohms reading between common and the other two terminals and a reading of 4.3 Ω between the start and run terminals most likely has:
• In a system with multiple evaporators, which device helps regulate evaporator pressure across the evaporators?
• During recovery, where should the low-side gauge be connected?
• The capacitor testing function on many multimeters will NOT read correctly if:
• Which of the following is an effect of small carbon particles inside the refrigeration system?
• Moisture in the refrigeration system can cause which of the following?
• The contacts of a current starting relay are:
• The potential relay coil is wired:
• In a performance log, baseline condenser data is typically recorded as?
• An example of baseline condenser data is which temperature value?
• When installing a solenoid valve, which statement is correct?
• Electrical components can generally be divided into two groups:
• Which of the following is a possible cause of underfeeding the TEV?
• The starting relay contacts are described as normally open. What does this mean when the coil is not energized?
• The coil of a potential relay used with small single-phase compressors should have a resistance of approximately:
• Which condition is most consistent with an acidic oil found in a hermetic compressor, requiring action?
• If a technician needs to check the refrigerant pressures on a system with a small charge:
• To increase the operating superheat on a thermostatic expansion valve:
• If you try to remove tubing before all the brazing material is molten, the tubing will:
• Which refrigeration device would most likely be installed in the discharge line leaving the compressor to prevent liquid refrigerant from draining from a raised condenser into the compressor head?
• When debrazing a joint on a refrigeration system, often
• Which statement correctly describes common desiccants used in driers?
• RLA stands for which term in refrigeration systems?
• A commonly observed sign that the filter drier is blocked is
• With the compressor off, a technician compares the pressure of an air-cooled condenser with the pressure given on the PT chart for that refrigerant and temperature. The system pressure is considerably higher than the pressure indicated on the PT chart for that refrigerant and temperature. This indicates that:
• Which item is not typically included in a baseline performance check?
• The advantage of ball valves over other types of manual refrigeration valves is that they:
• With three-phase compressors, a voltage imbalance of greater than ________ will cause the windings within a motor to generate heat beyond safe levels, leading to premature motor failure.
• If a filter drier becomes clogged, what symptom would you expect?
• What are the three main circuit characteristics commonly measured to troubleshoot electrical circuits?
• What gas is used for leak testing after reassembly of the system?
• Turning the thermostatic expansion valve adjusting stem clockwise would have which effect on operating superheat?
• The three major electrical defects in compressor motors that can be identified using an ohmmeter are:
• Noncondensable gases in the refrigeration system can cause which of the following?
• What effect do noncondensable gases have on system performance?
• What is the main advantage of a pressure relief valve on a receiver compared to a fusible plug?
• Baseline condenser data includes what type of measurement?
• A suction superheat measurement lower than the manufacturer's recommended superheat setting indicates that:
• Why is nitrogen used to purge the system before using the flushing solvent?
• Which line is connected to indicators if the liquid oil acid test kit cannot be used?
• On run capacitors, any sign of bulging of its body is a sign of a(n) ________ capacitor.
• What are the two basic types of relief valves used on refrigeration systems?
• Which statement describes the parameters included in a baseline performance check?
• If the maximum continuous current rating is 20 A, what is the approximate RLA?
• What is the material inside the filter drier called?
• Overdefrosting is caused by:
• What is the default state of the contacts in a potential relay?
• When recovering contaminated refrigerant, the high-side gauge should be connected to which line?
• Baseline condenser data helps to establish a reference for which variable?
• Which procedure should be followed to safely isolate a semihermetic compressor from system pressure?
• If an ohmmeter test shows infinite resistance between the terminals of a compressor winding, this indicates:
• A bulging body on a run capacitor indicates which condition?
• A suction superheat measurement higher than the manufacturers’ recommended setting indicates which condition?
• A healthy start winding test result would show:
• Baseline condenser data point commonly used to assess inlet conditions is?
• A crankcase pressure regulator is designed to prevent compressor suction pressure from rising above what value?
• The coil of a current relay used with small single-phase compressors should have a resistance of approximately 0.1 Ω. Which of the following is closest to that value?
• Noncondensable gases in the refrigeration system can cause which of the following other symptoms?
• Baseline condenser data typically includes which measurement?
• Which condition is NOT considered when selecting a CPR valve?
• Along with the refrigerant that is being discharged, compressors will discharge which of the following as it leaves the compressor?
• On a starting relay, the component can be tested to see if it is electrically acceptable using a standard ________ or capacitance meter.
• When should a technician record a system's baseline data?
• To check the condition of the compressor's motor windings, a technician will need to measure the resistance of the windings using:
• What visual clue on a system can indicate the presence of a refrigerant leak?
• Which statement best describes the flow characteristic of ball valves in refrigeration systems?
• A winding that shows continuity to the compressor housing indicates:
• One basic rule a technician must follow while searching for a leak is to:
• Which of the following is another effect of small carbon particles inside the refrigeration system?
• To check for electrical potential at a switch or a load, technicians use a(n).
• When flushing the system, you should:
• To isolate a semihermetic compressor from system pressure:
• When cleaning up after a compressor burnout, immediately after you recover the refrigerant, you should
• The coil of a current relay used with small single-phase compressors should have a resistance of approximately:
• Which gas is used to purge the flush after flushing lines and coils?
• Which combination of system parameters is typically observed when noncondensable gases are present in the refrigerant circuit?
• What must technicians measure after a system cleanup to verify performance?
• You should flush the system:
• Noncondensable gases can contribute to which performance issue?
• When troubleshooting, small-capacity refrigeration systems:
• What does a reading of 0 Ω on the run winding indicate?
• If a compressor start winding resistance test shows OL, which conclusion is most accurate?
• How does accumulated dirt on the condenser coil affect system operation?
• After a system cleanup, which evaporator value should be measured?
• Which option correctly identifies the two basic types of relief valves used on refrigeration systems?
• What does an evaporator pressure regulator primarily do?
• One method of elevating system liquid pressure is to
• Which parameter is an example of baseline condenser data?