2A672 Volume 2 Ure (Aircraft) Questions

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2A672 Volume 2 Ure (Aircraft) Questions - Quiz

A person aiming to become aerospace ground equipment journeyman is charged with diagnosing any malfunctions and repairing the equipment. Before they assign a person to repair the equipment they should ensure that they perform troubleshooting on the equipment. Give the question below on volume two a try before beginning on the next volume.


Questions and Answers
  • 1. 

    During operation of the EPU-6/E frequesncy converter it is determined that E and F pin voltage in not needed for the aircraft.  The operator places the Loop/bypass/28 V to aircraft switch to what position?

    • A.

      28 V to aircraft

    • B.

      Neutral

    • C.

      Bypass

    • D.

      Loop

    Correct Answer
    C. Bypass
    Explanation
    During the operation of the EPU-6/E frequency converter, if it is determined that the E and F pin voltage is not needed for the aircraft, the operator should place the Loop/bypass/28 V to aircraft switch in the Bypass position.

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  • 2. 

    Which of the following components provides 525 VAC to the control transformer of the EPU-6/E frequency converter?

    • A.

      Input auto transformer

    • B.

      Output auto transformer

    • C.

      Input phase sequence transformer

    • D.

      Output phase sequence transformer

    Correct Answer
    A. Input auto transformer
    Explanation
    The correct answer is Input auto transformer. The input auto transformer provides 525 VAC to the control transformer of the EPU-6/E frequency converter.

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  • 3. 

    What EPU-6/E components receive potential directly from the input auto transformer?

    • A.

      Analog board and alarm display

    • B.

      Control transformer and voltage control

    • C.

      Input circuit breakers and display power supply

    • D.

      SCR voltage regulator and phase sequence transformer

    Correct Answer
    D. SCR voltage regulator and phase sequence transformer
    Explanation
    The SCR voltage regulator and phase sequence transformer receive potential directly from the input auto transformer.

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  • 4. 

    The control transformer perform on the EPU-6/E frequency converter provides

    • A.

      28 VDC for the aircraft contactor

    • B.

      240 VDC for the aircraft contactor

    • C.

      120 VAC for the operation of E and F line 28 VDC power supply

    • D.

      240 VAC for operation of E and F line 28 VDC power supply

    Correct Answer
    C. 120 VAC for the operation of E and F line 28 VDC power supply
    Explanation
    The control transformer on the EPU-6/E frequency converter provides 120 VAC for the operation of the E and F line 28 VDC power supply. This means that the control transformer converts the incoming voltage to 120 VAC, which is then used to power the E and F line 28 VDC power supply. This allows the power supply to operate and provide the necessary 28 VDC power to the aircraft contactor.

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  • 5. 

    What EPU-6/E frequency converter components must be inspected prior to use?

    • A.

      Air inlets for blockage

    • B.

      Wiring for secure mounting

    • C.

      Maintenance panels for corrosion

    • D.

      Interior air vents for secure mounting

    Correct Answer
    A. Air inlets for blockage
    Explanation
    The air inlets for blockage must be inspected prior to use in order to ensure proper functioning of the EPU-6/E frequency converter. If the air inlets are blocked, it can restrict the flow of air and lead to overheating of the components. Regular inspection of the air inlets will help prevent any potential blockages and ensure efficient operation of the frequency converter.

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  • 6. 

    During operation you determine that there is an undervoltage fault problem with the EPU-6/E frequency converter unit.  What component could be malfunctioning?

    • A.

      Analog board has failed

    • B.

      Output trim potentiometer is centered

    • C.

      Voltage control board potentiometer is shorted

    • D.

      Audible alarm switch is in the silence position

    Correct Answer
    A. Analog board has failed
    Explanation
    The correct answer is "Analog board has failed." If there is an undervoltage fault problem with the EPU-6/E frequency converter unit, it suggests that there is an issue with the analog board. The analog board is responsible for controlling and regulating the voltage in the unit, so if it fails, it can result in an undervoltage fault.

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  • 7. 

    During operation of the EPU-6/E frequency converter you determine that one phase voltage is lower than the other two phases.  What could cause this malfunction?

    • A.

      Malfunctioning transister

    • B.

      Burnt control transformer fuse

    • C.

      Improper SCR firing adjustment

    • D.

      Loose push-on connector on the output filter capacitor

    Correct Answer
    D. Loose push-on connector on the output filter capacitor
    Explanation
    A loose push-on connector on the output filter capacitor could cause one phase voltage to be lower than the other two phases. When the connector is loose, it can result in a poor connection, leading to a decrease in voltage in that particular phase. This can disrupt the proper functioning of the frequency converter and cause the observed malfunction.

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  • 8. 

    What -95 gas turbine compressor section supplies high-volume, low-pressure air for combustion, cooling, and bleed air output?

    • A.

      Turbine section

    • B.

      Accessory section

    • C.

      Compressor section

    • D.

      Air regulator section

    Correct Answer
    C. Compressor section
    Explanation
    The correct answer is compressor section. The compressor section of a gas turbine is responsible for supplying high-volume, low-pressure air for various purposes such as combustion, cooling, and bleed air output. It plays a crucial role in the overall functioning of the gas turbine by compressing the incoming air before it enters the combustion chamber. This compressed air is then mixed with fuel and ignited to produce the necessary power for the turbine. Additionally, the compressor section also provides air for cooling purposes and for other auxiliary systems in the turbine.

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  • 9. 

    The function of the deswirl ring on the -95 gas turbine compressor is to

    • A.

      Accelerate air

    • B.

      Increase air pressure

    • C.

      Decrease air velocity

    • D.

      Smooth turbulent air flow

    Correct Answer
    D. Smooth turbulent air flow
    Explanation
    The deswirl ring on the -95 gas turbine compressor is designed to smooth turbulent air flow. Turbulent air flow can cause inefficiencies and disruptions in the compressor's operation. The deswirl ring helps to eliminate or reduce turbulence, ensuring a more consistent and smooth flow of air through the compressor. This improves the overall performance and efficiency of the gas turbine compressor.

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  • 10. 

    What -95 component isolates the second-stage air from the operation of the first-stage compressor?

    • A.

      Interstage ducts

    • B.

      Interstage seal

    • C.

      Impellers

    • D.

      Inducers

    Correct Answer
    B. Interstage seal
    Explanation
    The interstage seal is the correct answer because it is a component that isolates the second-stage air from the operation of the first-stage compressor. It prevents any leakage of air between the two stages and ensures that the second-stage air is not affected by the operation of the first-stage compressor. This helps in maintaining the efficiency and performance of the compressor.

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  • 11. 

    What prevents overpressurization of the bearing cavity on a -95?

    • A.

      Oil jet

    • B.

      Oil cooler

    • C.

      Scavenge pump

    • D.

      Oil tank vent line

    Correct Answer
    D. Oil tank vent line
    Explanation
    The oil tank vent line prevents overpressurization of the bearing cavity on a -95. This is because the vent line allows excess pressure to escape from the oil tank, ensuring that the pressure within the bearing cavity remains at a safe level. Without the vent line, the pressure could build up and potentially cause damage to the bearing cavity.

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  • 12. 

    What -95 chambers are pressurized when the butterfly valve is closed?

    • A.

      1 and 3

    • B.

      2 and 4

    • C.

      1, 2, and 3

    • D.

      1, 3, and 4

    Correct Answer
    D. 1, 3, and 4
    Explanation
    When the butterfly valve is closed, chambers 1, 3, and 4 are pressurized. This means that the pressure is sealed off in these chambers and cannot escape. The other chambers, 2 and 5, are not pressurized because the butterfly valve is closed, preventing the flow of pressure into those chambers. Therefore, the correct answer is 1, 3, and 4.

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  • 13. 

    The -95's rate-metering valve prevents the butterfly valve from snapping open by bleeding air through the atmospheric bleed port from chamber

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    Correct Answer
    B. 2
    Explanation
    The explanation for the given answer is that the rate-metering valve in the -95 prevents the butterfly valve from opening suddenly by releasing air through the atmospheric bleed port from the chamber.

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  • 14. 

    What -95 component closes to complete the electrical circuit to the fuel solenoid and ignition unit?

    • A.

      Load switch

    • B.

      Oil pressure switch

    • C.

      Turbine start switch

    • D.

      35 percent centrifugal speed switch

    Correct Answer
    B. Oil pressure switch
    Explanation
    The oil pressure switch is responsible for completing the electrical circuit to the fuel solenoid and ignition unit. This switch is designed to detect the presence of sufficient oil pressure in the engine. Once the oil pressure reaches the required level, the switch closes the circuit, allowing the fuel solenoid and ignition unit to function properly. This ensures that the engine has the necessary oil pressure before starting, preventing any potential damage or malfunctions.

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  • 15. 

    Refer to foldout 2.  The -95 runs up to 60 percent but the battery is not charging.  What is the probable cause of this trouble?

    • A.

      K4 energized and its contacts closed

    • B.

      K3 de-energized and its contacts opened

    • C.

      K4 de-energized and its contacts closed

    • D.

      K3 de-energized and its contacts did not remain closed

    Correct Answer
    D. K3 de-energized and its contacts did not remain closed
    Explanation
    The probable cause of this trouble is that K3 was de-energized but its contacts did not remain closed. This means that the circuit that charges the battery was not able to complete, resulting in the battery not being charged.

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  • 16. 

    Refer to foldout 2.  During an ops check of a -95, you place the air load switch S2 in the ON position.  The butterfly valve starts to open at 95 percent.  What do you check?

    • A.

      SV2

    • B.

      S10

    • C.

      TD2

    • D.

      K6

    Correct Answer
    C. TD2
    Explanation
    During the ops check of a -95, when the air load switch S2 is placed in the ON position, the butterfly valve starts to open at 95 percent. In order to ensure that the butterfly valve is functioning correctly, you need to check TD2.

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  • 17. 

    Refer to foldout 2.  What -95 component energizes SV4?

    • A.

      Master switch

    • B.

      Air load valve

    • C.

      Air load switch

    • D.

      Oil pressure switch

    Correct Answer
    C. Air load switch
    Explanation
    The air load switch is the component that energizes SV4.

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  • 18. 

    What preliminary set-up step, if skipped, prevents the -95 from starting?

    • A.

      Set-up controls

    • B.

      Set parking brakes

    • C.

      Open and secure the exhaust door

    • D.

      Ensure the turbine air inlet and exhaust doors are free of obstructions

    Correct Answer
    C. Open and secure the exhaust door
    Explanation
    If the exhaust door is not opened and secured, the -95 will not be able to start. This is because the exhaust door allows for the release of exhaust gases from the turbine, which is necessary for the engine to function properly. If the door is not opened and secured, the exhaust gases will be trapped, leading to a buildup of pressure and preventing the engine from starting. Therefore, it is crucial to open and secure the exhaust door as a preliminary set-up step to ensure the -95 can start successfully.

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  • 19. 

    On the -95, discharge air pressure at 100 percent engine speed should indicate

    • A.

      55 +2 psig

    • B.

      45 +2 psig

    • C.

      35 +2 psig

    • D.

      25 +2 psig

    Correct Answer
    C. 35 +2 psig
    Explanation
    At 100 percent engine speed, the discharge air pressure on the -95 should indicate 35 +2 psig.

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  • 20. 

    Refer to foldout 2.  The -95 engine cranks but does not start.  What is the probable cause of this trouble?

    • A.

      CB3 s open

    • B.

      S9 is shorted

    • C.

      SV1 coil is open

    • D.

      K7 is not energized

    Correct Answer
    C. SV1 coil is open
    Explanation
    The probable cause of the engine cranking but not starting is that the SV1 coil is open. This means that there is a break in the electrical circuit of the SV1 coil, preventing it from receiving the necessary voltage to function properly. As a result, the coil is unable to generate the magnetic field required to initiate the engine's ignition process, leading to the engine not starting.

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  • 21. 

    The -95 does not shut down when the charging rate decreases to 12 amperes.  What is the probable cause of this trouble?

    • A.

      Air load switch

    • B.

      Fuel level relay K5

    • C.

      2 speed solenoid SV4

    • D.

      Battery charging module

    Correct Answer
    D. Battery charging module
    Explanation
    The probable cause of the trouble is the battery charging module. This module is responsible for regulating the charging rate of the battery. If the charging rate decreases to 12 amperes and the -95 does not shut down, it indicates a malfunction in the battery charging module, which is preventing the shutdown.

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  • 22. 

    When heat is applied to an ice cube and the ice starts to melt, it is

    • A.

      Super heat

    • B.

      Latent heat

    • C.

      Sensible heat

    • D.

      Convection heat

    Correct Answer
    B. Latent heat
    Explanation
    When heat is applied to an ice cube and it starts to melt, the process is known as latent heat. Latent heat refers to the heat energy absorbed or released during a phase change, such as the transition from solid to liquid. In this case, the ice cube absorbs heat energy from its surroundings, causing the ice molecules to gain enough energy to break their bonds and transition into a liquid state. This process does not result in a change in temperature, as the heat energy is used to overcome the intermolecular forces holding the ice together rather than increasing the kinetic energy of the molecules.

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  • 23. 

    The three methods of heat transfer are

    • A.

      Sensible, latent, and super heat

    • B.

      Sensible, convection, and conduction

    • C.

      Conduction, convection, and radiation

    • D.

      Conduction, convection, and super heat

    Correct Answer
    C. Conduction, convection, and radiation
    Explanation
    The correct answer is conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between objects or substances. Convection is the transfer of heat through the movement of fluids or gases. Radiation is the transfer of heat through electromagnetic waves, such as infrared radiation. These three methods are the primary ways in which heat is transferred from one object to another.

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  • 24. 

    The air flowing through an air conditioner is also called

    • A.

      Heat

    • B.

      Heat load

    • C.

      Pounds per minute (ppm)

    • D.

      Cubic feet per minute (cfm)

    Correct Answer
    B. Heat load
    Explanation
    The air flowing through an air conditioner is referred to as the "heat load" because it carries the thermal energy that needs to be removed or transferred by the air conditioner. The heat load represents the amount of heat that needs to be removed from the space being cooled, and it is a crucial factor in determining the capacity and efficiency requirements of the air conditioning system.

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  • 25. 

    While you are doing an ops check of an air conditioner, you notice the unit is short cycling.  What do you do to correct this trouble?

    • A.

      Increase the heat load

    • B.

      Lower the refrigerant charge

    • C.

      Check the receiver outlet valve

    • D.

      Decrease the setting of the LPCO

    Correct Answer
    C. Check the receiver outlet valve
    Explanation
    Short cycling in an air conditioner occurs when the unit turns on and off too frequently, which can lead to inefficient cooling and increased wear and tear on the system. Checking the receiver outlet valve can help correct this issue because a faulty or clogged valve can cause improper refrigerant flow, leading to short cycling. By ensuring that the valve is functioning properly, the refrigerant flow can be regulated, allowing the air conditioner to operate more efficiently and prevent frequent cycling.

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  • 26. 

    Bubbles in an air conditioner refrigeration system sight glass probably indicate

    • A.

      Refrigerant overcharge

    • B.

      A low refrigerant charge

    • C.

      High discharge temperature

    • D.

      Low discharge air temperature

    Correct Answer
    B. A low refrigerant charge
    Explanation
    Bubbles in an air conditioner refrigeration system sight glass probably indicate a low refrigerant charge. When there is a low refrigerant charge, the system does not have enough refrigerant to properly cool the air. This can lead to reduced cooling performance and the formation of bubbles in the sight glass. The bubbles indicate that the refrigerant is boiling or evaporating too quickly, which is a sign of low refrigerant levels.

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  • 27. 

    What MA-3D air conditioner component controls refrigerant flow into the evaporator?

    • A.

      Quench valve

    • B.

      TXV solenoid valve

    • C.

      Hot gas bypass circuit

    • D.

      Electric expansion valve

    Correct Answer
    D. Electric expansion valve
    Explanation
    The electric expansion valve is the component that controls the flow of refrigerant into the evaporator in an MA-3D air conditioner. It regulates the amount of refrigerant that enters the evaporator coil, allowing for precise control of the cooling process. By adjusting the opening of the valve, the electric expansion valve can ensure that the right amount of refrigerant is supplied to the evaporator, optimizing the cooling efficiency of the air conditioner.

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  • 28. 

    The temperature controller on an MA-3D air conditioner opens the hot gas bypass valve if the

    • A.

      Air pressure is too low so the boiling point of the R134a must be increased

    • B.

      Suction air pressure is too high so the boiling point of the refrigerant can be decreased

    • C.

      Suction pressure is too low so the boiling point of the refrigerant must be increased to increase the output air temperature

    • D.

      Suction pressure is too high so the boiling point of the refrigerant must be decreased to decrease the output air temperature

    Correct Answer
    C. Suction pressure is too low so the boiling point of the refrigerant must be increased to increase the output air temperature
    Explanation
    The correct answer is that if the suction pressure is too low, the boiling point of the refrigerant must be increased to increase the output air temperature. When the suction pressure is too low, it means that there is not enough refrigerant entering the compressor. This can result in a decrease in the boiling point of the refrigerant, which can lead to a decrease in the output air temperature. To compensate for this, the temperature controller opens the hot gas bypass valve, which increases the boiling point of the refrigerant and ultimately increases the output air temperature.

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  • 29. 

    You place the MA-3D air conditioner SW1 in the START position, but the engine does not operate.  What is the probable cause of this trouble?

    • A.

      K7 contacts are closed

    • B.

      Overspeed switch is closed

    • C.

      Oil pressure switch is closed

    • D.

      Override switch is not closed

    Correct Answer
    D. Override switch is not closed
    Explanation
    The probable cause of the engine not operating when the MA-3D air conditioner SW1 is in the START position is that the override switch is not closed.

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  • 30. 

    Refer to foldouts 4 and 5.  What relay prevents the MA-3D air conditioner pumpdown light from illuminating in the cool mode?

    • A.

      K8

    • B.

      K2

    • C.

      TC

    • D.

      S4

    Correct Answer
    A. K8
    Explanation
    The relay K8 prevents the MA-3D air conditioner pumpdown light from illuminating in the cool mode.

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  • 31. 

    The engine on the MA-3D air conditioner is operating at 1,250 rpm, but the blower clutch does not engage.  What do you do?

    • A.

      Replace SW2

    • B.

      Replace the engine speed control

    • C.

      Nothing, this is normal operation; the blower clutch energizes at governed speed

    • D.

      Check the MPU to make sure it's sending the proper signal to the engine speed control

    Correct Answer
    C. Nothing, this is normal operation; the blower clutch energizes at governed speed
    Explanation
    The correct answer is "nothing, this is normal operation; the blower clutch energizes at governed speed". In this scenario, there is no need to take any action as the blower clutch will engage at the governed speed. The engine is operating at 1,250 rpm, but the blower clutch does not engage because it only energizes at the governed speed. Therefore, there is no issue with the air conditioner and no action is required.

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  • 32. 

    What MA-3D air conditioner component provides 24 VAC for operation of the temperature controller?

    • A.

      Generator (G1)

    • B.

      Alternator (G2)

    • C.

      Power monitor relay (PMR)

    • D.

      Transformer rectifier (TR1)

    Correct Answer
    C. Power monitor relay (PMR)
    Explanation
    The power monitor relay (PMR) is the MA-3D air conditioner component that provides 24 VAC for operation of the temperature controller. This means that the PMR is responsible for supplying the necessary voltage to power the temperature controller, allowing it to function properly. The generator (G1) and alternator (G2) are not mentioned as components that provide 24 VAC, and the transformer rectifier (TR1) is not specified as a source of power for the temperature controller. Therefore, the correct answer is the power monitor relay (PMR).

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  • 33. 

    The MA-3D air conditioner radiator fan stops operating.  Where do you start troubleshooting?

    • A.

      K2

    • B.

      K4

    • C.

      G2

    • D.

      CB2

    Correct Answer
    B. K4
    Explanation
    To troubleshoot the issue of the MA-3D air conditioner radiator fan not operating, you should start by checking K4. This suggests that K4 is a possible source of the problem and needs to be examined. However, without further context or information about the components and their functions, it is difficult to provide a more specific explanation for why K4 is the correct answer.

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  • 34. 

    While you are operating on MA-3D air conditioner, the output air temperature is too high, so you set the temperature control to maximum cooling.  The temperature controller sends a signal to

    • A.

      B7 which steps closed to meter R143a into the evaporator

    • B.

      B7 which steps open to meter R134a into the evaporator

    • C.

      The quench valve which opens to aid in cooling

    • D.

      S1 and S2 which open to aid in cooling

    Correct Answer
    B. B7 which steps open to meter R134a into the evaporator
    Explanation
    The correct answer is B7 which steps open to meter R134a into the evaporator. When the output air temperature of the MA-3D air conditioner is too high, setting the temperature control to maximum cooling triggers the temperature controller to send a signal to B7. B7 then steps open to meter R134a into the evaporator. This action helps to cool down the air and lower the temperature.

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  • 35. 

    What MA-3D air conditioner safety component de-energizes the compressor clutch?

    • A.

      Low-pressure cutout (LOTO) closing

    • B.

      Oil pressure cutout (OPCO) closing

    • C.

      Temperature controller (TC) breaking the circuit to K2

    • D.

      Suction pressure rising to 5 psi

    Correct Answer
    C. Temperature controller (TC) breaking the circuit to K2
    Explanation
    The temperature controller (TC) is responsible for monitoring the temperature of the air conditioner. When the temperature reaches a certain level, the TC breaks the circuit to K2, which de-energizes the compressor clutch. This prevents the compressor from running and helps to maintain the desired temperature. The low-pressure cutout (LOTO) closing, oil pressure cutout (OPCO) closing, and suction pressure rising to 5 psi are not directly related to de-energizing the compressor clutch.

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  • 36. 

    What type of refrigeration system leak occurs when the pressure within the system is less than atmospheric pressure?

    • A.

      Vacuum leaks

    • B.

      Inward leaks

    • C.

      Outward leaks

    • D.

      Pressure leaks

    Correct Answer
    B. Inward leaks
    Explanation
    Inward leaks occur in a refrigeration system when the pressure within the system is less than atmospheric pressure. This means that the refrigerant is leaking from the surroundings into the system, causing the pressure to decrease. These leaks can be problematic as they can lead to a loss of refrigerant and a decrease in system efficiency. It is important to identify and fix inward leaks to maintain the proper functioning of the refrigeration system.

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  • 37. 

    What type of engine starter does the ACE 802S air conditioner use?

    • A.

      Air

    • B.

      Manual

    • C.

      Electric

    • D.

      Hydraulic

    Correct Answer
    A. Air
    Explanation
    The ACE 802S air conditioner uses an air engine starter.

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  • 38. 

    What medium is used to lubricate the engine starter on the ACE 802S air conditioner?

    • A.

      Air

    • B.

      Oil

    • C.

      Fuel

    • D.

      Coolant

    Correct Answer
    C. Fuel
    Explanation
    The medium used to lubricate the engine starter on the ACE 802S air conditioner is fuel. Fuel is commonly used in engines as a lubricant to reduce friction and ensure smooth operation of the starter. It provides the necessary lubrication to prevent wear and tear on the engine components, allowing the starter to function effectively.

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  • 39. 

    The compressor switch on the ACE 802S must be held in the HOLD position when engaging the compressor in order to

    • A.

      Build up oil pressure

    • B.

      Defrost the evaporator

    • C.

      Allow the oil and discharge pressures to stabilize

    • D.

      Ensure the engine is at governed speed before engaging compressor

    Correct Answer
    C. Allow the oil and discharge pressures to stabilize
    Explanation
    When engaging the compressor on the ACE 802S, holding the compressor switch in the HOLD position allows the oil and discharge pressures to stabilize. This is important because the compressor needs stable oil and discharge pressures to function properly and efficiently. By holding the switch in the HOLD position, it ensures that the pressures have enough time to stabilize before the compressor is fully engaged. This helps to prevent any potential damage or issues that could arise from unstable pressures.

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  • 40. 

    When the ACE 802S compressor is in the HOLD position, what is the compressor displacement?

    • A.

      Errratic

    • B.

      Constant

    • C.

      Minimum

    • D.

      Maximum

    Correct Answer
    B. Constant
    Explanation
    When the ACE 802S compressor is in the HOLD position, the compressor displacement remains constant. This means that the amount of air being compressed and delivered by the compressor does not change while it is in the HOLD position.

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  • 41. 

    What does the heat boost system on the ACE802S air conditioner use to trim output air temperature?

    • A.

      Air

    • B.

      Refrigerant

    • C.

      Engine coolant

    • D.

      Electric heater

    Correct Answer
    C. Engine coolant
    Explanation
    The heat boost system on the ACE802S air conditioner uses engine coolant to trim the output air temperature. Engine coolant is a liquid that circulates through the engine and absorbs heat. By utilizing the engine coolant, the air conditioner can adjust the temperature of the output air, providing a boost of heat when needed. This allows for more precise control over the air temperature and ensures optimal comfort for the user.

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  • 42. 

    What ACE 802S air conditioner components divide the refrigerant system high-pressure side from the low-pressure side?

    • A.

      Compressor and expansion valve

    • B.

      Condenser and expansion valve

    • C.

      Compressor and condenser

    • D.

      Condenser and evaporator

    Correct Answer
    A. Compressor and expansion valve
    Explanation
    The compressor and expansion valve are the components that divide the refrigerant system high-pressure side from the low-pressure side. The compressor is responsible for compressing the refrigerant and raising its pressure, while the expansion valve controls the flow of the refrigerant into the low-pressure side, where it can evaporate and absorb heat. The condenser and evaporator are not involved in dividing the high and low-pressure sides, but rather play a role in the heat exchange process.

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  • 43. 

    What ACE 802S air conditioner system "supercharges" the compressor?

    • A.

      Defrost

    • B.

      Heat boost

    • C.

      Vapor injection

    • D.

      Liquid injection

    Correct Answer
    C. Vapor injection
    Explanation
    Vapor injection is the ACE 802S air conditioner system that "supercharges" the compressor. This technique involves injecting refrigerant vapor into the compressor, which helps to increase its efficiency and cooling capacity. By introducing vapor into the compressor, it helps to cool down the motor and prevents overheating, allowing the compressor to work more effectively. This results in improved performance and energy efficiency of the air conditioning system.

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  • 44. 

    What valve must be opened prior to starting the engine on the ACE 802S air conditioner system?

    • A.

      Air shutoff

    • B.

      Fuel shutoff

    • C.

      Coolant control

    • D.

      Refrigerant control

    Correct Answer
    A. Air shutoff
    Explanation
    The correct answer is air shutoff. Prior to starting the engine on the ACE 802S air conditioner system, the air shutoff valve must be opened. This valve controls the flow of air into the system and needs to be open for the engine to start and the air conditioner to function properly.

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  • 45. 

    What is the first troubleshooting step that must be accomplished when a unit comes in with a write-up in the forms?

    • A.

      Perform a service inspection

    • B.

      Perform an operational check

    • C.

      Verify the problem actually exists

    • D.

      Recognize the write-up as a malfunction

    Correct Answer
    D. Recognize the write-up as a malfunction
    Explanation
    The first troubleshooting step that must be accomplished when a unit comes in with a write-up in the forms is to recognize the write-up as a malfunction. This means acknowledging that there is a reported issue or problem with the unit. By recognizing the write-up as a malfunction, the technician can then proceed with further steps to diagnose and address the specific problem.

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  • 46. 

    What power source operates the heater/combustion section of the new generation heater (NGH)?

    • A.

      12 VDC

    • B.

      120 VAC

    • C.

      Hydraulic motor

    • D.

      Diesel engine only

    Correct Answer
    B. 120 VAC
    Explanation
    The heater/combustion section of the new generation heater (NGH) is operated by a 120 VAC power source.

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  • 47. 

    How does the new generation heater (NGH) keep output air temperature within programmed limits?

    • A.

      Burner control unit (BCU) uses outlet air sensors to compare air temperature with programmed value, cycling the fuel burner on and off to maintain temperature

    • B.

      Heater control unit (HCU) uses outlet air sensors to compare air temperature with programmed value, cycling the fuel burner on and off to maintain temperature

    • C.

      A photocell monitors combustion and activates the BCU to cycle the fuel burner on and off to maintain temperature

    • D.

      An electronic thermostat cycles the main air fan on and off to maintain temperature

    Correct Answer
    B. Heater control unit (HCU) uses outlet air sensors to compare air temperature with programmed value, cycling the fuel burner on and off to maintain temperature
    Explanation
    The correct answer is that the heater control unit (HCU) uses outlet air sensors to compare air temperature with the programmed value. It then cycles the fuel burner on and off to maintain the desired temperature. This means that the HCU constantly monitors the outlet air temperature and adjusts the fuel burner accordingly to ensure that the output air temperature remains within the programmed limits.

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  • 48. 

    What adjustment on the new generation heater (NGH) prevents coking in the combustion section?

    • A.

      Fuel pressure

    • B.

      Air/fuel ratio

    • C.

      Igniter timing

    • D.

      Fuel spray pattern

    Correct Answer
    B. Air/fuel ratio
    Explanation
    The air/fuel ratio is the correct answer because it refers to the ratio of air to fuel that is being supplied to the combustion section of the new generation heater (NGH). By adjusting the air/fuel ratio, the amount of air and fuel being mixed can be optimized to ensure complete combustion and prevent the formation of coke or carbon deposits. A proper air/fuel ratio helps to maintain efficient and clean combustion, reducing the risk of coking and improving the overall performance of the heater.

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  • 49. 

    How does the photocell on the new generation heater (NGH) verify the flame in the burner tube?

    • A.

      The photocell's thermal contacts open when heat increases

    • B.

      The photocell's thermal contacts close when heat increases

    • C.

      The photocell's resistance decreases in the presence of light

    • D.

      The photocell's resistance increases in the presence of light

    Correct Answer
    C. The photocell's resistance decreases in the presence of light
    Explanation
    The photocell's resistance decreases in the presence of light. This means that when the flame in the burner tube is present and emitting light, the photocell's resistance will decrease. This change in resistance is used by the NGH to verify the presence of the flame.

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  • 50. 

    When troubleshooting a defective new generation heater (NGH) charging system, what component do you check first?

    • A.

      Charge coil

    • B.

      Alternator G1

    • C.

      Ignition switch

    • D.

      Charge regulator

    Correct Answer
    C. Ignition switch
    Explanation
    When troubleshooting a defective new generation heater (NGH) charging system, the first component to check is the ignition switch. The ignition switch is responsible for supplying power to the charging system and controls the flow of electricity from the battery to the NGH. If the ignition switch is faulty or not functioning properly, it can disrupt the charging system and prevent it from working correctly. Therefore, checking the ignition switch is crucial in identifying and resolving any issues with the NGH charging system.

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