Maintenance And Troubleshooting Trivia Quiz!

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| By Enorab

Enorab

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Quizzes Created: 6 | Total Attempts: 3,485

Questions: 64 | Attempts: 224 | Updated: Mar 21, 2023

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Questions and Answers

1.

To safely check an electrical component for continuity or resistance, you would turn
- A.
  
  On the power and disconnnect at least one lead from the meter
- B.
  
  Off the power and disconnect at least one lead from the meter
- C.
  
  On the power and disconnect at least one lead from the component
- D.
  
  Off the power and disconnect at least one lead from the component
Correct Answer
D. Off the power and disconnect at least one lead from the component

Explanation
To safely check an electrical component for continuity or resistance, it is important to turn off the power and disconnect at least one lead from the component. This is because working with live electrical circuits can be dangerous and may result in electric shock or damage to the meter or the component. By turning off the power and disconnecting at least one lead, you ensure that there is no electrical current flowing through the circuit, making it safe to perform the continuity or resistance test.

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2.

Which thermostat terminal passes power to the heat relay?
- A.
  
  R
- B.
  
  G
- C.
  
  W
- D.
  
  Y
Correct Answer
C. W

Explanation
The W terminal passes power to the heat relay.

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3.

Which thermostat terminal passes power to the indoor fan?
- A.
  
  R
- B.
  
  G
- C.
  
  W
- D.
  
  Y
Correct Answer
B. G

Explanation
The G terminal on a thermostat is responsible for passing power to the indoor fan. When the thermostat calls for the fan to turn on, it sends a signal to the G terminal, which then activates the fan relay and allows power to flow to the fan. This terminal is commonly used in heating and cooling systems to control the operation of the fan.

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4.

Which fan circuit contacts must be closed to pass power to the fan motor?
- A.
  
  Fan realy
- B.
  
  Fan speed relay
- C.
  
  Evaporator relay
- D.
  
  Condenser relay
Correct Answer
A. Fan realy

Explanation
The fan relay is responsible for controlling the power supply to the fan motor. In order for power to be passed to the fan motor, the contacts of the fan relay must be closed. This allows the electrical current to flow from the power source to the fan motor, enabling it to operate.

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5.

The three components that operate in the cooling mode are the
- A.
  
  Compressor, the evaporator, and the outdoor fan
- B.
  
  Indoor fan, the compressor, and the outdoor fan
- C.
  
  Comrpessor, the indoor fan, and the defrost cycle
- D.
  
  Outdoor fan, the indoor fan, and auxiliary heat
Correct Answer
B. Indoor fan, the compressor, and the outdoor fan

Explanation
The correct answer is indoor fan, the compressor, and the outdoor fan. In the cooling mode, the indoor fan helps circulate the cool air throughout the room, while the compressor is responsible for compressing and cooling the refrigerant. The outdoor fan helps dissipate the heat from the refrigerant to the outside environment, completing the cooling cycle.

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6.

Most manufacturers illustrate the wiring in their equipment through the use of
- A.
  
  Pictoral and line diagrams
- B.
  
  Line and sectional diagrams
- C.
  
  Sectional and pictoral diagrams
- D.
  
  Sectional and enhanced diamgrams
Correct Answer
A. Pictoral and line diagrams

Explanation
Manufacturers typically use pictorial and line diagrams to illustrate the wiring in their equipment. Pictorial diagrams provide a visual representation of the components and their connections, making it easier for technicians to understand the wiring layout. On the other hand, line diagrams use standardized symbols to represent the electrical components and their interconnections. By combining these two types of diagrams, manufacturers can provide a comprehensive and clear representation of the equipment's wiring, ensuring efficient installation and troubleshooting processes.

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7.

You turn the indoor fan switch on a thermostat to the FAN ON position. When you do, the indoor fan motor does not come on. A possible cause of the problem is that there is
- A.
  
  Control voltage
- B.
  
  No control voltage
- C.
  
  Too much control voltage
- D.
  
  Not enough control voltage
Correct Answer
B. No control voltage

Explanation
If the indoor fan motor does not come on when the indoor fan switch is turned on, a possible cause of the problem is that there is no control voltage. This means that the thermostat is not sending the necessary electrical signal to activate the fan motor. It could be due to a faulty thermostat, a wiring issue, or a problem with the power supply.

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8.

You use your volt-ohm-milliammeter to check a transformer. You find it has an open. In this situation, the probable trouble is
- A.
  
  No control voltage
- B.
  
  A burned transformer
- C.
  
  No power to the G terminal
- D.
  
  A wire burned off the compressor
Correct Answer
B. A burned transformer

Explanation
In this situation, the probable trouble is a burned transformer. This means that the transformer has suffered damage, possibly due to overheating or a fault in the electrical circuit. As a result, the transformer is no longer functioning properly and may need to be replaced.

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9.

On a trouble call, you determine that voltage is present from R to Y at the thermostat but no voltage is present at the condenser contactor. In this situation, you would suspect that the
- A.
  
  R wire is broken
- B.
  
  Contacts are broken
- C.
  
  Y wire is broken
- D.
  
  R and Y wires are both broken
Correct Answer
C. Y wire is broken

Explanation
In this situation, if voltage is present from R to Y at the thermostat but no voltage is present at the condenser contactor, it suggests that the Y wire is broken. The Y wire is responsible for transmitting the signal from the thermostat to the condenser contactor, so if it is broken, the voltage will not reach the contactor. This would explain why there is voltage at the thermostat but not at the contactor.

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10.

Which terminals would you use to determine why a thermostat does not pass power to the relays when a split-system air-conditioner unit is in the cooling mode?
- A.
  
  R, G, & W
- B.
  
  R, G, & Y
- C.
  
  V, B, & W
- D.
  
  V, B, & Y
Correct Answer
B. R, G, & Y

Explanation
To determine why a thermostat does not pass power to the relays when a split-system air-conditioner unit is in the cooling mode, you would use the R, G, and Y terminals. The R terminal is used for power, the G terminal is used for the fan, and the Y terminal is used for the compressor. By checking these terminals, you can troubleshoot and identify any issues with power supply, fan operation, or compressor activation, which could be causing the thermostat to not pass power to the relays.

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11.

After you have disabled a motor disconnect, you lock and tag the panel. After this, you should be sure to keep the only key
- A.
  
  At the shop
- B.
  
  On your person
- C.
  
  With your crew leader
- D.
  
  With your shop supervisor
Correct Answer
B. On your person

Explanation
After locking and tagging the panel, it is important to keep the only key on your person. This means that you should have the key with you at all times, rather than leaving it at the shop, with your crew leader, or with your shop supervisor. Keeping the key on your person ensures that you have control over who can access the panel and prevents unauthorized individuals from tampering with the motor disconnect.

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12.

Mechanical motor problems normally occur at the
- A.
  
  Pulley or belt drive
- B.
  
  Bearings or the shaft
- C.
  
  Pulleys or the shafts
- D.
  
  End bells or ball bearings
Correct Answer
B. Bearings or the shaft

Explanation
Mechanical motor problems typically arise at the bearings or the shaft. Bearings are essential components of a motor as they support the rotating shaft, allowing it to spin smoothly. Over time, bearings can wear out or become damaged, leading to issues such as excessive noise, vibration, or even complete motor failure. Similarly, problems with the shaft, such as misalignment or excessive play, can cause the motor to malfunction. Therefore, it is crucial to regularly inspect and maintain the bearings and shaft to prevent and address any potential motor problems.

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13.

Most assemblies are held on the motor shaft by
- A.
  
  Setscrews
- B.
  
  Snap rings
- C.
  
  Lock pins
- D.
  
  O-rings
Correct Answer
A. Setscrews

Explanation
Setscrews are commonly used to hold assemblies on a motor shaft because they provide a secure and adjustable connection. Setscrews have a threaded hole that allows them to be tightened against the shaft, creating friction and preventing the assembly from slipping or rotating. This method is widely used in various applications because setscrews are easy to install and remove, making them a convenient choice for securing assemblies on motor shafts.

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14.

If the motor drive pulley and the driven pulley are out of line, strain will be imposed on the
- A.
  
  Starting circuit
- B.
  
  Fram mount
- C.
  
  Motor air system
- D.
  
  Shafts' drive mechanism
Correct Answer
D. Shafts' drive mechanism

Explanation
If the motor drive pulley and the driven pulley are out of line, strain will be imposed on the shafts' drive mechanism. When the pulleys are misaligned, it causes the shafts to be misaligned as well. This misalignment puts stress on the drive mechanism of the shafts, which can lead to increased wear and tear, decreased efficiency, and potential damage to the system. It is important to ensure proper alignment of the pulleys to prevent strain on the shafts' drive mechanism.

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15.

A short circuit will occur in the windings of a motor when the conductors in the windings
- A.
  
  Touch each other
- B.
  
  Expand and contract
- C.
  
  Pull apart from each other
- D.
  
  Create a high amperage draw
Correct Answer
A. Touch each other

Explanation
When the conductors in the windings of a motor touch each other, it creates a path of low resistance for the current to flow through. This results in a short circuit, where the current bypasses the intended circuit and flows directly between the touching conductors. This can cause excessive current flow, overheating, and potentially damage the motor or other components in the circuit.

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16.

To check for a short circuit from a motor winding to ground, you would use
- A.
  
  A voltmeter
- B.
  
  An ohmmeter
- C.
  
  An anmeter
- D.
  
  A clamp-on meter
Correct Answer
B. An ohmmeter

Explanation
To check for a short circuit from a motor winding to ground, an ohmmeter would be used. An ohmmeter is specifically designed to measure resistance and can determine if there is a low resistance path between the motor winding and ground. By connecting the ohmmeter to the motor winding and measuring the resistance, any unexpected low resistance readings would indicate a short circuit. This helps in identifying and diagnosing potential issues in the motor's electrical system.

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17.

A run capacitor on an eletric motor is constructed as a
- A.
  
  Metal can
- B.
  
  Paper can
- C.
  
  Plastic can
- D.
  
  Bakelite iron can
Correct Answer
A. Metal can

Explanation
The run capacitor on an electric motor is constructed as a metal can because metal cans provide better durability and protection for the internal components of the capacitor. Metal cans are able to withstand high temperatures and provide better insulation, ensuring the capacitor's longevity and efficient operation. Additionally, metal cans are less prone to damage from external factors such as moisture or physical impact, making them a reliable choice for this application.

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18.

A start capacitor on an eletric motor is constructed as a
- A.
  
  Wet type
- B.
  
  Dry type
- C.
  
  Round type
- D.
  
  Square type
Correct Answer
B. Dry type

Explanation
The start capacitor on an electric motor is constructed as a dry type. This means that it does not contain any liquid or oil inside. Dry type capacitors are commonly used in motors because they are more reliable and have a longer lifespan compared to wet type capacitors. They are also less prone to leakage and corrosion. Additionally, dry type capacitors are more compact and can be easily installed in various motor designs. Therefore, using a dry type start capacitor ensures the efficient and safe operation of the electric motor.

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19.

The motor problems that can occur inside a hermetic compressor are
- A.
  
  A blown fuse, closed circuit, and grounded circuit
- B.
  
  A closed circuit, short circuit, and a blown fuse
- C.
  
  A grounded circuit, closed circuit, and a short circuit
- D.
  
  An open circuit, short circuit, and grounded circuit
Correct Answer
D. An open circuit, short circuit, and grounded circuit

Explanation
The correct answer is "an open circuit, short circuit, and grounded circuit". This answer accurately identifies the motor problems that can occur inside a hermetic compressor. An open circuit refers to a break in the electrical connection, causing a lack of current flow. A short circuit occurs when there is an unintended connection between two points in the circuit, resulting in excessive current flow. A grounded circuit refers to a connection between the circuit and the ground, which can cause electrical faults and damage to the motor.

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20.

A motor that has a bad run capacitor
- A.
  
  Will not start
- B.
  
  May run at normal speed
- C.
  
  May run at a lower-than-normal speed
- D.
  
  Will run at a higher-than-normal speed
Correct Answer
C. May run at a lower-than-normal speed

Explanation
A motor that has a bad run capacitor may run at a lower-than-normal speed because the run capacitor is responsible for providing an extra boost of power to the motor during start-up. Without a functioning run capacitor, the motor may struggle to start and may not be able to reach its normal operating speed. As a result, the motor may run at a lower speed than usual.

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21.

What type of electrical problems will a hermetic compressor have?
- A.
  
  Open circuit
- B.
  
  Short circuit
- C.
  
  Grounded circuit
- D.
  
  All of the above
Correct Answer
D. All of the above

Explanation
A hermetic compressor can experience all types of electrical problems, including open circuit, short circuit, and grounded circuit. An open circuit occurs when there is a break in the electrical connection, causing the compressor to not receive power. A short circuit happens when there is an unintended connection between two points, causing excessive current flow and potentially damaging the compressor. A grounded circuit occurs when an electrical conductor comes in contact with a ground, leading to potential safety hazards and malfunction of the compressor. Therefore, all of the mentioned options can be electrical problems for a hermetic compressor.

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22.

A single-phase condition in a three-phase motor can be caused by
- A.
  
  A defective start capacitor
- B.
  
  A burned motor
- C.
  
  A blown fuse
- D.
  
  A closed circuit
Correct Answer
C. A blown fuse

Explanation
A blown fuse can cause a single-phase condition in a three-phase motor because it disrupts the flow of electrical current to one or two phases, resulting in the motor only operating on a single phase. This can happen if the fuse is overloaded or if there is a short circuit in the motor's electrical system. When a fuse blows, it breaks the circuit and prevents the motor from receiving power from the affected phase(s), causing it to operate at reduced capacity or not at all.

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23.

What is the possible cause when a motor will not start, hums and trips on overload?
- A.
  
  Incorrect overload switch
- B.
  
  Open disconnect switch
- C.
  
  Incorrect power supply
- D.
  
  Open fuse or breaker
Correct Answer
C. Incorrect power supply

Explanation
If a motor will not start, hums, and trips on overload, the possible cause could be an incorrect power supply. This means that the motor is not receiving the correct voltage or current required for it to start and operate properly. This could be due to issues with the wiring, a faulty power source, or incorrect connections. It is important to ensure that the motor is receiving the correct power supply in order to prevent damage and ensure proper functioning.

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24.

The temperature range of a refrigeration system depends upon the
- A.
  
  Product being refrigerated
- B.
  
  Condensing temperature
- C.
  
  Size of the compressor
- D.
  
  Ambient temperature
Correct Answer
A. Product being refrigerated

Explanation
The temperature range of a refrigeration system depends on the product being refrigerated. Different products have different temperature requirements for storage or preservation. For example, certain perishable foods may require lower temperatures to prevent spoilage, while other products like beverages may only need a slightly cooler temperature. Therefore, the specific product being refrigerated determines the temperature range needed in the system.

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25.

To maintain 75 percent humidity in a refrigeration system with a temperature range of 25 to 45*F, the appropriate coil-to-air temperature would be
- A.
  
  8 to 12*F
- B.
  
  10 to 14*F
- C.
  
  12 to 16*F
- D.
  
  16 to 22*F
Correct Answer
D. 16 to 22*F

Explanation
To maintain 75 percent humidity in a refrigeration system with a temperature range of 25 to 45°F, the appropriate coil-to-air temperature would be 16 to 22°F. This range allows for the cooling of the air without causing excessive condensation, which could lead to moisture-related issues. By keeping the coil-to-air temperature within this range, the system can effectively maintain the desired humidity level while also preventing any potential problems associated with excessive moisture.

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26.

The box temperature for high-temperature refrigeration system start at
- A.
  
  30*F
- B.
  
  45*F
- C.
  
  50*F
- D.
  
  65*F
Correct Answer
B. 45*F

Explanation
The correct answer is 45*F. This is because high-temperature refrigeration systems typically require a higher starting temperature for the box temperature. Starting at 30*F would be too low and may not provide sufficient cooling, while starting at 50*F or 65*F would be too high and may result in overcooling or potential damage to the system. Therefore, 45*F is the most suitable starting temperature for a high-temperature refrigeration system.

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27.

When the compressor is off and the system is up to the highest point of its operating range, the evaporator coil pressure should correspond to the
- A.
  
  Compressor pressure
- B.
  
  Condenser pressure
- C.
  
  Air tmeperature in the box
- D.
  
  Air temperature at the condenser
Correct Answer
C. Air tmeperature in the box

Explanation
When the compressor is off and the system is up to the highest point of its operating range, the evaporator coil pressure should correspond to the air temperature in the box. This is because when the compressor is off, there is no refrigerant flow and therefore no pressure difference between the evaporator and condenser coils. The evaporator coil pressure will be equal to the pressure of the air inside the box, which is determined by the temperature of the air.

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28.

When the temperature of a refirgerateed space goes down, the compressor will have
- A.
  
  Less capacity because the suction gas gets thinner
- B.
  
  More capacity because the suction gas gets thinner
- C.
  
  Less capacity because the suction gas gets more dense
- D.
  
  More capacity because the suction gas gets more dense
Correct Answer
A. Less capacity because the suction gas gets thinner

Explanation
When the temperature of a refrigerated space goes down, the suction gas inside the compressor becomes thinner. This means that there is a decrease in the density of the gas. As a result, the compressor will have less capacity because the thinner gas will have a lower mass flow rate, leading to a decrease in the cooling capacity of the system. Therefore, the correct answer is less capacity because the suction gas gets thinner.

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29.

What condensing temperature is normally maintained to obtain adequate pressure drops across an expansion valve?
- A.
  
  95*F
- B.
  
  105*F
- C.
  
  115*F
- D.
  
  125*F
Correct Answer
B. 105*F

Explanation
To obtain adequate pressure drops across an expansion valve, a condensing temperature of 105°F is normally maintained. The pressure drop across the expansion valve is necessary for the refrigerant to undergo a phase change from a high-pressure liquid to a low-pressure vapor, which allows for cooling. If the pressure drop is too low, the refrigerant may not fully vaporize, leading to inefficient cooling. Conversely, if the pressure drop is too high, it can cause issues such as excessive noise, vibration, or even damage to the expansion valve. Therefore, maintaining a condensing temperature of 105°F helps to achieve the optimal pressure drop for efficient cooling.

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30.

What is the normal temperature difference between the inlet and the outlet water on s wastewater water-cooled condenser?
- A.
  
  25*F
- B.
  
  20*F
- C.
  
  15*F
- D.
  
  10*F
Correct Answer
D. 10*F

Explanation
The normal temperature difference between the inlet and outlet water on a wastewater water-cooled condenser is 10°F. This means that the outlet water is typically 10°F cooler than the inlet water. This temperature difference is important for the efficient operation of the condenser, as it allows for effective heat transfer and cooling of the wastewater.

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31.

What is the most likely problem if the temperature difference between the inlet and the outlet water in a water-cooled is lower than normal?
- A.
  
  Ther water flow is sifficient
- B.
  
  There is too much water flow
- C.
  
  There is not enough water flow
- D.
  
  The cooling tower fan just cycled on
Correct Answer
B. There is too much water flow

Explanation
If the temperature difference between the inlet and outlet water in a water-cooled system is lower than normal, it suggests that there is too much water flow. This means that the water is passing through the system too quickly, not allowing enough time for it to properly cool down. As a result, the temperature difference between the inlet and outlet water is reduced. To rectify this issue, the water flow needs to be adjusted to a more appropriate level to ensure efficient cooling.

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32.

What is the normal maximum reduction of temperature in a cooling tower water if the ambient wet-bulb temperature is 85*F?
- A.
  
  72*F
- B.
  
  75*F
- C.
  
  78*F
- D.
  
  81*F
Correct Answer
C. 78*F

Explanation
In a cooling tower, the maximum reduction of temperature is determined by the difference between the ambient wet-bulb temperature and the temperature of the water leaving the tower. The wet-bulb temperature represents the lowest temperature that can be achieved through evaporation. Therefore, if the ambient wet-bulb temperature is 85°F, the normal maximum reduction of temperature in the cooling tower water would be 78°F, as this represents the maximum potential for evaporation and cooling.

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33.

What conditions are an indication of an overcharge in a system that is not equipped with an automatic expansion valve?
- A.
  
  Low suction pressure and high discharge pressure
- B.
  
  High suction pressure and low discharge pressure
- C.
  
  Low suction pressure and low discharge pressure
- D.
  
  High suction pressure and high discharge pressure
Correct Answer
D. High suction pressure and high discharge pressure

Explanation
When a system is not equipped with an automatic expansion valve, high suction pressure and high discharge pressure are indications of an overcharge. This means that there is an excessive amount of refrigerant in the system, causing the pressure to rise in both the suction and discharge lines. This can lead to inefficient cooling and potential damage to the system components.

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34.

The most probable causes of an inefficient evaporator are
- A.
  
  A dirty coil and a fan running too slow
- B.
  
  A dirty coil and a high suction pressure
- C.
  
  Too much airflow and a high suction pressure
- D.
  
  Too much airflow and a fan running too slow
Correct Answer
A. A dirty coil and a fan running too slow

Explanation
An inefficient evaporator can be caused by a dirty coil and a fan running too slow. A dirty coil reduces the heat transfer efficiency, making the evaporator less effective in cooling the air. Additionally, a fan running too slow can result in insufficient airflow across the coil, further reducing the cooling capacity. Both of these factors contribute to the inefficiency of the evaporator.

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35.

What conditions are an indication of a low charge in a system that is not equipped with an automatic expansion valve?
- A.
  
  Low suction pressure and high discharge pressure
- B.
  
  High suction pressure and low discharge pressure
- C.
  
  Low suction pressure and low discharge pressure
- D.
  
  High suction prssure and high discharge pressure
Correct Answer
C. Low suction pressure and low discharge pressure

Explanation
A low charge in a system without an automatic expansion valve can be indicated by low suction pressure and low discharge pressure. This means that there is not enough refrigerant in the system to maintain proper pressure levels during operation. Low suction pressure indicates a lack of refrigerant entering the compressor, while low discharge pressure suggests a reduced amount of refrigerant being pumped out of the compressor. Both of these conditions point towards a low charge in the system.

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36.

If the condenser in a refrigeration system cannot remove the heat from the refrigerant, the
- A.
  
  Suction pressure will decrease
- B.
  
  Discharge pressure will increase
- C.
  
  Liquid-line temperature will decrease
- D.
  
  Suction line will frost back to the compressor
Correct Answer
B. Discharge pressure will increase

Explanation
If the condenser in a refrigeration system cannot remove the heat from the refrigerant, it will cause a buildup of pressure in the system. This is because the heat cannot be dissipated, leading to an increase in the discharge pressure.

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37.

When a partial restriction occurs in the liquid line, the point of the restriction will act like
- A.
  
  An evaporator
- B.
  
  A condenser
- C.
  
  A compressor
- D.
  
  An expansion device
Correct Answer
D. An expansion device

Explanation
When a partial restriction occurs in the liquid line, the point of the restriction will act like an expansion device. This is because an expansion device is responsible for reducing the pressure of the refrigerant and controlling its flow into the evaporator. In the case of a partial restriction, the restricted point in the liquid line will cause a drop in pressure, similar to what an expansion device does. This drop in pressure allows the refrigerant to expand and evaporate, facilitating the cooling process.

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38.

A compressor that is not pumping to full capacity will have
- A.
  
  High suction and low head pressure
- B.
  
  High suction and high heah pressure
- C.
  
  Low suction and low head pressure
- D.
  
  Low suction and high head pressure
Correct Answer
A. High suction and low head pressure

Explanation
When a compressor is not pumping to full capacity, it means that it is not able to draw in and compress the refrigerant effectively. This results in high suction pressure, as the compressor is struggling to pull in enough refrigerant. On the other hand, the head pressure, which is the pressure of the refrigerant leaving the compressor, will be low because the compressor is not able to compress the refrigerant properly. Therefore, the correct answer is high suction and low head pressure.

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39.

You have removed and recovered the refrigerant from a system and solder repaired a leak. Before you recharge the unit, you must first perform
- A.
  
  A 4-hour standing vacuum test
- B.
  
  An operational test of the system
- C.
  
  Recurring maintenance
- D.
  
  A leak check
Correct Answer
D. A leak check

Explanation
Before recharging the unit with refrigerant after repairing a leak, it is necessary to perform a leak check. This is done to ensure that there are no remaining leaks in the system that could cause the refrigerant to escape again. By conducting a leak check, any potential leaks can be identified and repaired before recharging the unit, ensuring that the system will function properly and efficiently.

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40.

Calculate the discharge pressure for an R–502 system operating at 95*F outside ambient temperature.
- A.
  
  95*F + 15*F = 110*F and 245 psig
- B.
  
  95*F + 20*F = 115*F and 265 psig
- C.
  
  95*F + 25*F = 120*F and 286 psig
- D.
  
  95*F + 30*F = 125*F and 301 psig
Correct Answer
D. 95*F + 30*F = 125*F and 301 psig
41.

Which is an indication that the defrost system is not operating properly?
- A.
  
  Defrost is terminated by the time clock.
- B.
  
  The unit operates with excessive head pressure
- C.
  
  The unit operates with excessive suction pressure.
- D.
  
  Manually initiated defrost is terminated by the temperature sensing device
Correct Answer
D. Manually initiated defrost is terminated by the temperature sensing device

Explanation
When the defrost system is not operating properly, the manually initiated defrost is terminated by the temperature sensing device. This means that even if the defrost is manually started, it will not continue until the temperature sensing device detects that the appropriate temperature has been reached. This indicates that the defrost system is not functioning correctly and may need to be repaired or replaced.

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42.

Which is designed to stop the defrost cycle of a low-temperature walk-in?
- A.
  
  Low-pressure motor control
- B.
  
  High-pressure safety switch.
- C.
  
  Termination switch.
- D.
  
  Oil pressure switch.
Correct Answer
C. Termination switch.

Explanation
A termination switch is designed to stop the defrost cycle of a low-temperature walk-in. This switch is responsible for sensing when the defrost cycle has reached its desired temperature and then terminating the cycle. It ensures that the walk-in does not continue to defrost for longer than necessary, preventing excessive energy consumption and potential damage to the walk-in. The other options, such as low-pressure motor control, high-pressure safety switch, and oil pressure switch, are not specifically designed for this purpose.

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43.

When the thermal bulb of an expansion valve is loose from the suction line, you would expect the
- A.
  
  Suction line to be warmer than normal
- B.
  
  Suction line to be colder than normal
- C.
  
  Discharge line to be warmer than normal.
- D.
  
  Discharge line to be colder than normal
Correct Answer
B. Suction line to be colder than normal

Explanation
When the thermal bulb of an expansion valve is loose from the suction line, it can result in a loss of refrigerant flow control. This means that less refrigerant will be allowed into the evaporator coil, resulting in reduced cooling capacity. As a result, the suction line, which carries the cool refrigerant from the evaporator to the compressor, will be colder than normal. This is because there is less refrigerant flowing through the system to absorb heat from the surroundings.

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44.

What problems can a high-efficiency water filtration system cause for an ice machine?
- A.
  
  None, these systems are mandatory.
- B.
  
  The system can increase the conductivity of the water.
- C.
  
  The system can decrease the conductivity of the water.
- D.
  
  None, these systems do not change the conductivity of water and cause no problems.
Correct Answer
C. The system can decrease the conductivity of the water.

Explanation
A high-efficiency water filtration system can cause problems for an ice machine by decreasing the conductivity of the water. This can lead to issues such as poor ice quality, slower ice production, and potential damage to the ice machine components. Lower conductivity water may not be able to effectively transfer heat, affecting the ice-making process. Additionally, decreased conductivity can also impact the taste and clarity of the ice produced. Therefore, while high-efficiency water filtration systems are important, they can have negative effects on ice machines if they decrease the water conductivity.

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45.

A refrigerator may have condensation (sweat) on the outside of the cabinet if the
- A.
  
  Mullion heater is defective.
- B.
  
  Defrost time clock is defective
- C.
  
  Defrost termination switch is defective.
- D.
  
  Evaporator fan motor is defective
Correct Answer
A. Mullion heater is defective.

Explanation
If a refrigerator has condensation (sweat) on the outside of the cabinet, it indicates that the mullion heater is defective. The mullion heater is responsible for preventing condensation by maintaining the exterior surface of the refrigerator at a temperature above the dew point. If the mullion heater is not functioning properly, it fails to keep the surface warm, resulting in condensation forming on the outside of the cabinet.

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46.

When an exact replacement compressor for a refrigerator cannot be obtained, you would gather all data from the
- A.
  
  Compressor nameplate only
- B.
  
  Refrigerator nameplate only.
- C.
  
  Refrigerator nameplate and draw a diagram of the compressor lines and mounting
- D.
  
  Compressor nameplate and draw a diagram of the compressor lines and mounting
Correct Answer
D. Compressor nameplate and draw a diagram of the compressor lines and mounting

Explanation
When an exact replacement compressor for a refrigerator cannot be obtained, the best course of action is to gather all data from the compressor nameplate and draw a diagram of the compressor lines and mounting. This is because the compressor nameplate contains important information such as the model number, voltage, and refrigerant type, which are necessary for finding a suitable replacement. Additionally, drawing a diagram of the compressor lines and mounting will help ensure that the replacement compressor is installed correctly and fits properly in the refrigerator.

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47.

You should never use hand tools in a
- A.
  
  Hot electrical panel
- B.
  
  Cold electrical panel
- C.
  
  Cold package air conditioner
- D.
  
  Hot package air conditioner
Correct Answer
A. Hot electrical panel

Explanation
Using hand tools in a hot electrical panel can be dangerous because the heat can cause the tools to become hot, increasing the risk of burns or injury. Additionally, the heat can affect the insulation of the wires, increasing the risk of electrical shock. It is important to wait for the panel to cool down before attempting any work to ensure safety.

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48.

You can reduce the danger involved in attaching high-pressure gauges on a manifold by stuttin off the
- A.
  
  Refrigerant and allow to cool
- B.
  
  High side and allowing the pressures to equalize
- C.
  
  Valves and allowing the pressures to equalize
- D.
  
  Unit an allowing the pressures to equalize
Correct Answer
D. Unit an allowing the pressures to equalize
49.

To verify that the refrigerant is boiling at the correct temperature for the low side of the system at a given load condition, you would use
- A.
  
  The high-side gauge readings
- B.
  
  The low-side gauge readings
- C.
  
  Ultralow pressure gauge readings
- D.
  
  All of the above
Correct Answer
B. The low-side gauge readings

Explanation
To verify that the refrigerant is boiling at the correct temperature for the low side of the system at a given load condition, you would use the low-side gauge readings. This is because the low-side gauge provides information about the pressure and temperature of the refrigerant as it enters the evaporator coil. By monitoring the low-side gauge readings, you can ensure that the refrigerant is boiling at the correct temperature, which is crucial for efficient cooling and proper functioning of the system. The high-side gauge readings and ultralow pressure gauge readings may provide additional information, but they are not specifically used to verify the boiling temperature of the refrigerant on the low side.

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50.

To check the relationship of the condensing refrigerant to the ambient air temperature, you would use
- A.
  
  The high-side gauge readings
- B.
  
  The low-side gauge readings
- C.
  
  Ultralow pressure gauge readings
- D.
  
  All of the above
Correct Answer
A. The high-side gauge readings

Explanation
To check the relationship of the condensing refrigerant to the ambient air temperature, you would use the high-side gauge readings. The high-side gauge measures the pressure of the refrigerant after it has been compressed by the compressor. By comparing the high-side gauge readings with the ambient air temperature, you can determine if the condensing process is occurring effectively. If the high-side gauge readings are too high or too low in relation to the ambient air temperature, it may indicate a problem with the condenser or other components of the refrigeration system.

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