2A672 Volume 2 Ure Frequesncy Converter
Volume URE for 2A672 Volume 2
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. BypassExplanation
During the operation of the EPU-6/E frequency converter, it is determined that the E and F pin voltage is not needed for the aircraft. In this scenario, the operator should place the Loop/bypass/28 V to aircraft switch in the "Bypass" position. This allows the voltage to bypass the E and F pins and directly supply the aircraft with the 28 V power it requires.Rate this question:
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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 transformerExplanation
The correct answer is the Input auto transformer. The input auto transformer is responsible for providing 525 VAC to the control transformer of the EPU-6/E frequency converter. This component helps in regulating and transforming the voltage from the input power source to the desired level for the control transformer. It plays a crucial role in ensuring the proper functioning of the frequency converter by supplying the necessary voltage to the control transformer.Rate this question:
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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 transformerExplanation
The SCR voltage regulator and phase sequence transformer receive potential directly from the input auto transformer.Rate this question:
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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 supplyExplanation
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 transformer converts the incoming voltage to 120 VAC, which is then used to power the E and F line 28 VDC power supply. This voltage is necessary for the proper functioning of the power supply, allowing it to provide the required 28 VDC power to the aircraft contactor.Rate this question:
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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 blockageExplanation
Prior to use, it is important to inspect the air inlets for blockage in the EPU-6/E frequency converter. This is because blocked air inlets can restrict the flow of air into the converter, leading to overheating and potential damage. By checking the air inlets for blockage, any obstructions can be cleared, ensuring proper airflow and preventing any potential issues.Rate this question:
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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 failedExplanation
The correct answer is that the analog board has failed. This means that there is an issue with the analog board, which is responsible for converting analog signals into digital signals. This malfunction could be causing the undervoltage fault problem with the EPU-6/E frequency converter unit.Rate this question:
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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 capacitorExplanation
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 and create an imbalance in the voltage distribution. This can lead to lower voltage in one phase compared to the others.Rate this question:
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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 sectionExplanation
The correct answer is the compressor section. In a gas turbine, the compressor section is responsible for supplying high-volume, low-pressure air for various purposes such as combustion, cooling, and bleed air output. It compresses the incoming air, increasing its pressure before it enters the combustion chamber. This section plays a crucial role in the overall functioning of the gas turbine by ensuring the proper flow and pressure of air for combustion and other necessary operations.Rate this question:
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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 flowExplanation
The deswirl ring on the -95 gas turbine compressor is responsible for smoothing turbulent air flow. Turbulence in the air flow can cause inefficiencies and disruptions in the compressor's operation. The deswirl ring helps to eliminate or reduce these disturbances, ensuring a smoother and more controlled airflow. This allows for better performance and efficiency of the compressor, ultimately improving the overall functioning of the gas turbine.Rate this question:
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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 sealExplanation
The interstage seal is the correct answer because it is a component that separates the second-stage air from the operation of the first-stage compressor. This seal ensures that the air from the first-stage compressor does not mix with the air from the second-stage, allowing for efficient and controlled compression in each stage. The interstage seal helps maintain the integrity and performance of both stages of the compressor.Rate this question:
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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 lineExplanation
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, preventing it from building up and causing overpressurization.Rate this question:
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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 4Explanation
When the butterfly valve is closed, chambers 1, 3, and 4 are pressurized.Rate this question:
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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. 2Explanation
The correct answer is 2 because the rate-metering valve on the -95 prevents the butterfly valve from snapping open. This is achieved by bleeding air through the atmospheric bleed port from the chamber.Rate this question:
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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 switchExplanation
The oil pressure switch is the component that closes to complete the electrical circuit to the fuel solenoid and ignition unit. This switch is designed to monitor the oil pressure in the engine. When the oil pressure reaches a certain level, the switch closes, allowing the electrical current to flow and activate the fuel solenoid and ignition unit. This ensures that the engine has sufficient oil pressure before allowing the fuel and ignition systems to operate, which is crucial for the safe and efficient functioning of the engine.Rate this question:
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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 closedExplanation
The probable cause of this trouble is that K3 de-energized and its contacts did not remain closed. This means that the circuit that charges the battery is not able to complete, resulting in the battery not charging.Rate this question:
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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. TD2Explanation
During an 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 this scenario, you would check TD2.Rate this question:
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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 switchExplanation
The air load switch energizes SV4 according to foldout 2.Rate this question:
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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 doorExplanation
If the exhaust door is not opened and secured, the -95 will not be able to start. This is because the exhaust door allows the release of exhaust gases from the turbine. If it is closed or not properly secured, the exhaust gases will not be able to escape, which can cause a buildup of pressure and prevent the turbine from starting. Therefore, opening and securing the exhaust door is a crucial preliminary step in the set-up process to ensure the -95 can start successfully.Rate this question:
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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 psigExplanation
At 100 percent engine speed, the discharge air pressure on the -95 should indicate 35 +2 psig.Rate this question:
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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 openExplanation
The probable cause of the engine cranking but not starting is that the SV1 coil is open. An open coil means that there is a break in the electrical circuit, preventing the coil from receiving power and functioning properly. Without the coil functioning, the necessary spark to ignite the fuel mixture in the engine cannot be generated, resulting in the engine failing to start.Rate this question:
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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 moduleExplanation
The probable cause of the trouble is the battery charging module. This module is responsible for regulating the charging rate of the battery. If it is not functioning properly, it may not shut down the -95 when the charging rate decreases to 12 amperes.Rate this question:
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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 heatExplanation
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 melting or vaporization, without a change in temperature. In this case, the ice cube absorbs heat energy from its surroundings, causing the solid ice to change into liquid water. This absorption of heat energy is known as latent heat because it is not causing a change in temperature, but rather a change in the state of matter.Rate this question:
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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 radiationExplanation
The correct answer is conduction, convection, and radiation. These three methods of heat transfer are fundamental concepts in thermodynamics. Conduction is the transfer of heat through direct contact between objects or materials. 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 play a crucial role in various natural and technological processes, and understanding them is essential in fields like engineering, physics, and meteorology.Rate this question:
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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 loadExplanation
The air flowing through an air conditioner is commonly referred to as the "heat load" because it carries the heat from the indoor space to be removed or cooled by the air conditioning system. The heat load is the amount of heat energy that needs to be transferred or removed from the space to maintain a desired temperature. It is an important factor in determining the capacity and efficiency of an air conditioning system.Rate this question:
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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 valveExplanation
Short cycling in an air conditioner refers to the unit turning on and off frequently, which can be caused by various issues. Checking the receiver outlet valve is a valid step to take in order to correct this trouble. The receiver outlet valve controls the flow of refrigerant from the receiver to the evaporator, and if it is malfunctioning or blocked, it can cause the unit to short cycle. By checking the valve, one can identify and address any issues with it, potentially resolving the problem of short cycling.Rate this question:
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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 chargeExplanation
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 cause the refrigerant to boil and create bubbles in the sight glass. It is important to have the correct amount of refrigerant in the system to ensure efficient and effective cooling.Rate this question:
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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 valveExplanation
The electric expansion valve is the component that controls the flow of refrigerant into the evaporator in an MA-3D air conditioner. It is responsible for regulating the amount of refrigerant that enters the evaporator coil, ensuring optimal cooling efficiency. By opening and closing, the electric expansion valve adjusts the flow rate based on the cooling demand, maintaining a consistent temperature in the evaporator and preventing the system from freezing or overheating.Rate this question:
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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 temperatureExplanation
The correct answer is suction pressure is too low so 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 output air temperature. To compensate for this, the temperature controller opens the hot gas bypass valve, which increases the boiling point of the refrigerant. By increasing the boiling point, the temperature of the refrigerant increases, which in turn increases the output air temperature.Rate this question:
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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 closedExplanation
The probable cause of the engine not operating when the MA-3D air conditioner SW1 is placed in the START position is that the override switch is not closed.Rate this question:
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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. K8Explanation
The relay K8 prevents the MA-3D air conditioner pumpdown light from illuminating in the cool mode.Rate this question:
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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 speedExplanation
The correct answer is nothing, this is normal operation; the blower clutch energizes at governed speed. In this scenario, the engine on the air conditioner is operating at 1,250 rpm, but the blower clutch does not engage. However, this is considered normal operation as the blower clutch energizes at governed speed, which means it will only engage at a certain predetermined speed set by the system. Therefore, there is no need to replace any components or check the MPU signal in this case.Rate this question:
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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) component of the MA-3D air conditioner provides 24 VAC for operation of the temperature controller. This means that the PMR is responsible for supplying the necessary electrical power to the temperature controller, allowing it to function properly. The generator (G1) and alternator (G2) are unlikely to provide the specific voltage required for the temperature controller, while the transformer rectifier (TR1) is not mentioned in relation to providing power for the temperature controller. Therefore, the correct answer is the power monitor relay (PMR).Rate this question:
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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. K4Explanation
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 component or a connection point related to the operation of the fan. By inspecting K4, you can identify any potential faults or malfunctions that may be causing the fan to stop operating.Rate this question:
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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 evaporatorExplanation
When the output air temperature of the MA-3D air conditioner is too high, setting the temperature control to maximum cooling is the appropriate action to take. In this scenario, the temperature controller sends a signal to B7, which steps open to meter R134a into the evaporator. This means that B7 opens up to allow R134a refrigerant to enter the evaporator, which aids in cooling the air.Rate this question:
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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 K2Explanation
The temperature controller (TC) is responsible for monitoring the temperature and maintaining it within a specific range. In the case of the MA-3D air conditioner, when the temperature exceeds the desired limit, the TC breaks the circuit to K2, which in turn de-energizes the compressor clutch. This action prevents the compressor from running and helps to ensure the safety of the air conditioning system.Rate this question:
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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 leaksExplanation
Inward leaks occur in a refrigeration system when the pressure within the system is less than atmospheric pressure. This means that air or other substances from the outside are being drawn into the system, causing a decrease in pressure. These leaks can lead to a loss of refrigerant and a decrease in the system's efficiency.Rate this question:
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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. AirExplanation
The ACE 802S air conditioner uses an air engine starter.Rate this question:
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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. FuelExplanation
Fuel is used to lubricate the engine starter on the ACE 802S air conditioner. Fuel is essential for the engine to start and run smoothly. It acts as a lubricant for the moving parts of the engine, reducing friction and preventing wear and tear. Without fuel, the engine starter would not be able to function properly, leading to difficulties in starting the air conditioner. Therefore, fuel is the correct medium for lubricating the engine starter on the ACE 802S air conditioner.Rate this question:
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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 stabilizeExplanation
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 pressure levels for proper operation. By holding the switch in the HOLD position, it ensures that the pressures have reached a stable state before fully engaging the compressor.Rate this question:
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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. ConstantExplanation
When the ACE 802S compressor is in the HOLD position, the compressor displacement remains constant. This means that the volume of air compressed by the compressor remains the same, regardless of any external factors or changes in operating conditions. The compressor does not vary its displacement while in the HOLD position, ensuring a consistent output of compressed air.Rate this question:
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Mar 21, 2023Quiz Edited by
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Jan 08, 2012Quiz Created by
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