1.
Normal mid-temp refrigeration temperature is approximately __ degrees.
Correct Answer
C. 40
Explanation
The normal mid-temp refrigeration temperature is approximately 40 degrees. This temperature is commonly used for storing perishable items like fruits, vegetables, and dairy products. It is considered an ideal temperature to slow down the growth of bacteria and extend the shelf life of these items. It is important to maintain this temperature to ensure the quality and safety of the stored products.
2.
Heat is absorbed by evaporating a liquid refrigerant in the ___.
Correct Answer
C. Evaporator
Explanation
The correct answer is Evaporator. In a refrigeration system, heat is absorbed by evaporating a liquid refrigerant in the evaporator. The evaporator is the component where the refrigerant evaporates, absorbing heat from the surroundings and cooling the area. This process allows the refrigerant to change from a liquid to a gas, which is then compressed and condensed in the compressor and condenser respectively. The receiver is a storage tank for the refrigerant.
3.
Heat flows in what direction?
Correct Answer
B. Warm to cold
Explanation
Heat flows from a region of higher temperature to a region of lower temperature. This is known as the second law of thermodynamics. When there is a temperature difference between two objects, heat energy will transfer from the warmer object to the cooler object until they reach thermal equilibrium. Therefore, the correct answer is "Warm to cold."
4.
Heat may be transferred from one body to another by ___.
Correct Answer
D. All of the above
Explanation
Heat can be transferred from one body to another by radiation, conduction, and convection. Radiation is the transfer of heat through electromagnetic waves, such as heat from the sun reaching the Earth. Conduction is the transfer of heat through direct contact between two objects, for example, when you touch a hot stove. Convection is the transfer of heat through the movement of fluids or gases, like the circulation of warm air in a room. Therefore, all three methods can be used to transfer heat between bodies.
5.
Refrigerant fluids are ___.
Correct Answer
D. Both A and B
Explanation
Refrigerant fluids are both fluids that absorb heat inside a cabinet and fluids that release heat outside of a cabinet. This means that they have the ability to absorb heat from the surroundings within a cabinet, cooling the area, and also to release heat to the surroundings outside of the cabinet, dissipating the heat.
6.
Which of the following illustrates the principle of convection?
Correct Answer
A. Movement of heat by fluid or air
Explanation
The principle of convection is illustrated by the movement of heat through fluid or air. Convection occurs when warmer particles in a fluid or air rise, creating a flow that transfers heat from one place to another. This is commonly observed in phenomena such as boiling water, where heat is transferred from the bottom of the pot to the surface through the rising motion of the heated water.
7.
Why do some technicians use the reamer to clean the end of the copper tubing?
Correct Answer
B. To remove the burrs
Explanation
Technicians use the reamer to clean the end of the copper tubing in order to remove the burrs. Burrs are small metal projections that can form on the inside or outside of the tubing during the cutting or bending process. These burrs can obstruct the flow of fluids or cause damage to other components. By using a reamer, technicians can remove these burrs and ensure a smooth and clean surface, allowing for proper installation and functioning of the tubing.
8.
What indicates that correct brazing temperature has been reached?
Correct Answer
B. A green color appears in the flame
Explanation
When brazing, the correct temperature is indicated by a green color appearing in the flame. This is because certain metals, such as copper, produce a green flame when heated to the correct brazing temperature. The green color is a visual cue for the brazing technician to know that the metal is at the right temperature for the brazing process to occur effectively.
9.
When should you push and pull on a wrench?
Correct Answer
D. Always pull
Explanation
When using a wrench, it is generally recommended to pull in order to loosen a bolt or nut and push to tighten it. This is because pulling allows for greater leverage and control, making it easier to apply force in the desired direction. Pushing, on the other hand, may result in less control and could potentially cause the wrench to slip or strip the bolt. Therefore, it is best practice to always pull when using a wrench.
10.
Refrigeration service valve wrench is used to __.
Correct Answer
D. All of the above
Explanation
A refrigeration service valve wrench is a versatile tool that can be used for various purposes related to the valve. It can be used to front sit the valve, meaning to position it towards the front. It can also be used to back sit the valve, which involves positioning it towards the back. Additionally, the wrench can be used to mid position the valve, which refers to placing it in the middle position. Therefore, the correct answer is "All of the above" as the wrench can be used for all these actions.
11.
In an AEV or AXV system, when does the needle valve open?
Correct Answer
C. When the compressor reduces the pressure in the evaporator
12.
In the TEV or TXV system, when does the needle valve open?
Correct Answer
D. When the evaporator pressure is low and the temp is above normal
Explanation
In a TEV or TXV system, the needle valve opens when the evaporator pressure is low and the temperature is above normal. This is because the needle valve is responsible for regulating the flow of refrigerant into the evaporator coil. When the evaporator pressure is low, it indicates that there is a need for more refrigerant to enter the coil in order to maintain the desired temperature. Therefore, the needle valve opens to allow more refrigerant to flow into the evaporator and increase the pressure and temperature.
13.
Why do most domestic refrigerators have a defrost system?
Correct Answer
C. Frost buildup on evaporator reduces efficiency
Explanation
Most domestic refrigerators have a defrost system because frost buildup on the evaporator reduces efficiency. When frost accumulates on the evaporator, it acts as an insulator, preventing the efficient transfer of heat. This reduces the cooling capacity of the refrigerator and may lead to longer running times and higher energy consumption. Therefore, a defrost system is necessary to remove the frost and maintain the optimal performance of the refrigerator.
14.
In a compression refrigerator, oil buildup can cause a problem in the ___
Correct Answer
C. Motor
Explanation
In a compression refrigerator, oil buildup can cause a problem in the motor. The motor is responsible for driving the compressor, which is essential for the cooling process. If oil buildup occurs in the motor, it can hinder its performance and lead to overheating or malfunctioning. This can result in reduced cooling efficiency or complete failure of the refrigerator. Regular maintenance and cleaning of the motor are necessary to prevent oil buildup and ensure the smooth operation of the compression refrigerator.
15.
What control determines the refrigerator cabinet temperature?
Correct Answer
B. Temperature control
Explanation
The temperature control is responsible for determining the refrigerator cabinet temperature. It regulates the cooling system of the refrigerator, adjusting the temperature as needed to maintain the desired level. This control is essential in ensuring that the refrigerator maintains a consistent and appropriate temperature to keep food fresh and prevent spoilage.
16.
Automatic expansion valve usually adjusts the ___.
Correct Answer
D. Both B and C
Explanation
The automatic expansion valve usually adjusts both the temperature in the evaporator and the pressure in the evaporator. This valve is responsible for regulating the flow of refrigerant into the evaporator, ensuring that the temperature and pressure within the evaporator remain at optimal levels for efficient cooling. By adjusting these two factors, the valve helps maintain the overall performance and efficiency of the refrigeration system.
17.
Which type of compressors use crankshaft seal?
Correct Answer
B. Open-type
Explanation
Open-type compressors use a crankshaft seal. The crankshaft seal is a mechanical seal that prevents the leakage of refrigerant or lubricating oil from the crankcase of the compressor. In open-type compressors, the crankshaft is exposed to the surrounding atmosphere, making it necessary to have a seal to prevent any leakage. This type of compressor is commonly used in small to medium-sized refrigeration and air conditioning systems.
18.
The device that changes low pressure vapor to high pressure is called?
Correct Answer
D. Compressor
Explanation
A compressor is a device that is used to increase the pressure of a low pressure vapor. It achieves this by reducing the volume of the vapor, which in turn increases its pressure. This process is essential in various applications, such as air conditioning, refrigeration, and industrial processes, where the high pressure vapor is needed for efficient operation. The other options, metering device, open-type, and condenser, do not perform the function of increasing the pressure of a low pressure vapor.
19.
The device that changes liquid to vapor is called?
Correct Answer
C. Evaporator
Explanation
The device that changes liquid to vapor is called an evaporator. This device is commonly used in refrigeration and air conditioning systems. It works by absorbing heat from the surroundings, causing the liquid refrigerant to evaporate and turn into a gas. This phase change allows the evaporator to cool the surrounding environment.
20.
Why are expansion valves adjustable?
Correct Answer
D. Both A and B
Explanation
Expansion valves are adjustable to accommodate different altitudes and different types of refrigerants. Altitude affects the pressure and temperature at which a refrigerant evaporates and condenses, so adjusting the expansion valve ensures proper functioning at different altitudes. Similarly, different refrigerants have different properties and operating conditions, so the expansion valve needs to be adjustable to regulate the flow of each specific refrigerant. Therefore, the correct answer is "Both A and B."
21.
What force causes a thermal-electric expansion valve to open?
Correct Answer
C. An electromagnet
Explanation
An electromagnet is the force that causes a thermal-electric expansion valve to open. When an electric current is passed through the coil of the electromagnet, it creates a magnetic field that attracts a metal rod or plunger. This movement of the plunger opens the expansion valve, allowing the flow of refrigerant or fluid. The electromagnet provides a controlled and efficient means of opening the valve based on the electrical input, making it a suitable force for this purpose.
22.
What force causes the solenoid valve to open?
Correct Answer
C. An electromagnet
Explanation
An electromagnet is the force that causes the solenoid valve to open. When an electric current passes through the coil of the solenoid, it creates a magnetic field that attracts a metal plunger or armature, causing it to move and open the valve. The strength of the magnetic field can be controlled by adjusting the current, allowing for precise control of the valve opening and closing.
23.
In a refrigerator that has capillary tube, what controls the box temperature?
Correct Answer
D. Temperature control
Explanation
The temperature control is responsible for controlling the box temperature in a refrigerator with a capillary tube. It regulates the cooling process by turning the compressor on and off based on the desired temperature set by the user. The temperature control monitors the temperature inside the refrigerator and adjusts the cooling cycle accordingly to maintain a consistent temperature.
24.
What type of valve is used to reverse the flow of refrigerant in a heat pump?
Correct Answer
D. 4-way solenoid valve
Explanation
A 4-way solenoid valve is used to reverse the flow of refrigerant in a heat pump. This valve has four ports, allowing the refrigerant to flow in different directions depending on the position of the valve. By controlling the energization of the solenoid coil, the valve can switch the flow direction, allowing the heat pump to switch between heating and cooling modes. This valve is essential in the operation of a heat pump as it controls the direction of the refrigerant flow to achieve the desired heating or cooling effect.
25.
___ is a unit of electromotive force.
Correct Answer
D. Volt
Explanation
A volt is a unit of electromotive force, which measures the potential difference between two points in an electric circuit. It represents the amount of electrical pressure or push that causes electric charges to flow in a circuit. The higher the voltage, the greater the force that drives the electric current. Kilowatt, microfarad, and milliamps are not units of electromotive force, making them incorrect options.
26.
___ is a unit of electric current.
Correct Answer
C. Ampere
Explanation
An ampere is a unit of electric current. It is named after the French mathematician and physicist André-Marie Ampère, who is considered one of the founders of electromagnetism. The ampere is defined as one coulomb of charge passing through a conductor per second. It is used to measure the flow of electric charge in a circuit and is an essential unit in electrical engineering and physics.
27.
___ is a unit of capacitance.
Correct Answer
B. Microfarad
Explanation
A microfarad is a unit of capacitance, which measures the ability of a capacitor to store an electric charge. It is equal to one millionth of a farad, making it a very small unit of measurement. Capacitance is an important property in electrical circuits as it determines how much charge a capacitor can store for a given voltage. Therefore, the correct answer is Microfarad.
28.
___ is a unit of electrical power.
Correct Answer
A. Kilowatt
Explanation
A kilowatt is a unit of electrical power. It is commonly used to measure the rate at which electrical energy is consumed or produced. One kilowatt is equal to 1000 watts. It is frequently used in household appliances, as well as in industrial and commercial settings, to determine the amount of power needed or generated.
29.
Thermistors are used in refrigeration work ___.
Correct Answer
A. To measure temperatures
Explanation
Thermistors are used in refrigeration work to measure temperatures. Thermistors are temperature-sensitive resistors that change their resistance with temperature. In refrigeration systems, thermistors are commonly used as temperature sensors to monitor and control the temperature of the system. By measuring the resistance of the thermistor, the temperature can be accurately determined, allowing for precise temperature regulation in refrigeration applications.
30.
How many electrical terminals does a hermetic compressor motor have?
Correct Answer
C. Three
Explanation
A hermetic compressor motor typically has three electrical terminals. These terminals are used to connect the motor to an electrical power source, allowing it to operate. Each terminal serves a specific purpose, such as providing power, grounding, or controlling the motor's speed. Having three terminals ensures that the motor functions properly and safely.
31.
Bimetal switches will open if ___.
Correct Answer
D. Both A and B
Explanation
Bimetal switches are designed to open when the current load is too high or when there is poor air circulation. When the current load exceeds the capacity of the switch, it causes the bimetal strip to heat up and bend, opening the circuit. Similarly, if there is poor air circulation, the bimetal strip may not cool down properly, leading to it bending and opening the switch. Therefore, both A and B are correct explanations for why bimetal switches will open.
32.
The start capacitor is connected in ___ with the start winding.
Correct Answer
A. Series
Explanation
The start capacitor is connected in series with the start winding. This means that the start capacitor is connected in line with the start winding, creating a series circuit. In a series circuit, the current flows through each component in the circuit one after the other. Therefore, the start capacitor and start winding are connected in series to ensure proper starting of the motor.
33.
A hermetic system is a ___
Correct Answer
A. Motor and compressor in a dome
Explanation
A hermetic system refers to a motor and compressor that are enclosed within a dome or sealed container. This design ensures that the system is completely sealed and prevents any external contaminants from entering. The motor and compressor are both housed in the same unit, providing a compact and efficient solution. This design is commonly used in refrigeration and air conditioning systems.
34.
Compressor, fan and pump motors should be regularly cleaned to___.
Correct Answer
D. All of the above
Explanation
Regularly cleaning compressor, fan, and pump motors is important to remove dust, provide proper air circulation, and remove lint. Dust accumulation can hinder the performance and efficiency of the motors, while proper air circulation is necessary to prevent overheating. Additionally, lint buildup can cause blockages and reduce the motors' effectiveness. Therefore, cleaning these motors regularly ensures their optimal functioning and prevents potential issues caused by dust, lack of air circulation, and lint.
35.
Loose or dirty connection on a fan motor can cause ___.
Correct Answer
A. Voltage drop
Explanation
A loose or dirty connection on a fan motor can cause a voltage drop. This is because a loose or dirty connection can create resistance in the circuit, leading to a decrease in the voltage supplied to the fan motor. As a result, the fan motor may not receive enough voltage to operate at its intended speed or power, causing a drop in voltage.
36.
To test for shorts or grounds on the motor windings, use an ___.
Correct Answer
B. Ohmmeter
Explanation
An ohmmeter is used to measure the resistance in an electrical circuit. By testing the motor windings with an ohmmeter, one can determine if there are any shorts or grounds present. Shorts occur when there is an unintended connection between two points in the circuit, while grounds occur when a wire comes into contact with a conductive surface. By measuring the resistance, any abnormal readings can indicate the presence of a short or ground in the motor windings. Using a high voltage test instrument, voltmeter, or ammeter would not provide the necessary information to detect shorts or grounds in the motor windings.
37.
What is the common color used for ground wire?
Correct Answer
C. Green
Explanation
Green is the common color used for ground wire. Ground wires are used to provide a path for electrical currents to flow into the ground in the event of a fault or surge. The color green is used to easily identify and differentiate ground wires from other electrical wires. This standard color coding helps ensure safety and proper installation of electrical systems. Red, black, and white are commonly used for other purposes in electrical wiring, but green is specifically designated for ground wires.
38.
What is the purpose of a ladder diagram?
Correct Answer
B. To help troubleshoot a system
Explanation
A ladder diagram is a graphical representation of an electrical circuit commonly used in industrial automation systems. It consists of horizontal lines representing power and vertical lines representing the control logic. The purpose of a ladder diagram is to help troubleshoot a system by providing a visual representation of the electrical circuit. It allows technicians and engineers to easily identify faults, analyze the system's behavior, and make necessary adjustments or repairs. Additionally, ladder diagrams can also be used to identify the actual location of components within a system and provide a standard electrical circuit diagram.
39.
Identify the starting relay or relays used on hermetic compressors
Correct Answer
D. All of the above
Explanation
The correct answer is "All of the above" because hermetic compressors can use multiple types of starting relays. They can utilize current relays, which sense the current flowing through the compressor motor to determine when to switch from the start winding to the run winding. They can also use thermal relays, which monitor the temperature of the motor and switch the windings accordingly. Additionally, solid-state electronic relays can be used, which use electronic components to control the motor's starting and running process. Therefore, all three options - current, thermal, and solid-state electronic - can be used as starting relays on hermetic compressors.
40.
A compressor motor may be operated by ___.
Correct Answer
C. Both A and B
Explanation
A compressor motor may be operated by both low pressure control and temperature control. This means that the motor can be controlled and regulated based on both the pressure and temperature conditions. The low pressure control ensures that the motor operates within a specific pressure range, while the temperature control ensures that the motor does not overheat. By utilizing both controls, the compressor motor can maintain optimal performance and prevent any potential damage or malfunction.
41.
Which color cyliner designates R-134a?
Correct Answer
C. Sky Blue
Explanation
The color cylinder that designates R-134a is Sky Blue.
42.
Which of the following refrigerants are not CFCs?
Correct Answer
B. R-22
Explanation
R-22 is not a CFC (chlorofluorocarbon) because it does not contain any chlorine atoms. CFCs are known to be harmful to the ozone layer, and their production has been phased out due to environmental concerns. R-22 is actually a hydrochlorofluorocarbon (HCFC), which contains hydrogen, chlorine, fluorine, and carbon atoms. While HCFCs are also ozone-depleting substances, they have a lower ozone depletion potential compared to CFCs. R-22 is commonly used as a refrigerant in air conditioning systems, but its production and importation have been gradually reduced as part of international agreements to protect the ozone layer.
43.
Which color cylinder designates R-22?
Correct Answer
C. Light green
Explanation
The light green color designates R-22.
44.
Which of the following is an HFC refrigerant?
Correct Answer
C. R-134a
Explanation
R-134a is the correct answer because it is a hydrofluorocarbon (HFC) refrigerant. HFCs are commonly used as a replacement for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) due to their lower ozone depletion potential. R-12 and R-22 are both CFC refrigerants, while R-123 is an HCFC refrigerant.
45.
Which of the following is an HCFC refrigerant?
Correct Answer
C. R-22
Explanation
R-22 is the correct answer because it is an HCFC (hydrochlorofluorocarbon) refrigerant. HCFCs contain chlorine, which contributes to ozone depletion, but to a lesser extent than CFCs (chlorofluorocarbons). R-134a and R-11 are not HCFC refrigerants; R-134a is an HFC (hydrofluorocarbon) refrigerant, and R-11 is a CFC refrigerant.
46.
Which of the following is a refrigerant blend?
Correct Answer
C. R-409a
Explanation
R-409a is a refrigerant blend because it consists of a mixture of different refrigerants. It is composed of R-22, R-124, and R-142b. Refrigerant blends are commonly used in various cooling systems to achieve specific performance characteristics and to comply with environmental regulations.
47.
Why should refrigerant cylniders be filled to only 80% or capacity?
Correct Answer
D. Both A and B
Explanation
Refrigerant cylinders should be filled to only 80% of their capacity because liquid refrigerant expands when the temperature increases. If the cylinder is completely filled with liquid and it warms up, the expanding refrigerant can cause the cylinder to burst. Therefore, filling the cylinder to only 80% capacity allows for the expansion of the refrigerant without the risk of bursting the cylinder.
48.
Refrigeration contaminants are removed by ___.
Correct Answer
C. Both A and B
Explanation
Both oil separation and filtration are methods used to remove contaminants in refrigeration systems. Oil separation is the process of removing oil from the refrigerant, as oil can mix with the refrigerant and cause issues in the system. Filtration, on the other hand, involves removing solid particles and debris from the refrigerant. Both methods are important in maintaining the efficiency and proper functioning of refrigeration systems by ensuring that contaminants are removed. Therefore, the correct answer is "Both A and B."
49.
Refrigerant in a system should be disposed of by ___.
Correct Answer
C. Using recovery/recycling equipment
Explanation
The correct answer is using recovery/recycling equipment. This is because refrigerants contain harmful substances that can contribute to ozone depletion and climate change if released into the air. Therefore, it is important to properly dispose of refrigerants by using recovery/recycling equipment, which safely captures and recycles the refrigerant for reuse or ensures its proper disposal. Venting it into the air or bleeding off some of the charge into the air is not recommended as it can have negative environmental impacts.
50.
What refrigerant have the greatest negative effect on the ozone?
Correct Answer
A. CFC
Explanation
CFCs (chlorofluorocarbons) have the greatest negative effect on the ozone layer. These chemicals contain chlorine, which is released into the atmosphere and reacts with ozone molecules, causing their destruction. CFCs were commonly used in refrigeration and air conditioning systems, as well as in aerosol propellants. Due to their harmful impact on the ozone layer, the production and use of CFCs have been phased out under the Montreal Protocol. HCFCs (hydrochlorofluorocarbons) are also ozone-depleting substances, but their impact is less severe compared to CFCs. Azeotropic refrigerants are a type of blend that do not have a significant negative effect on the ozone layer.