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HVAC CDC's > Volume 5 > Flashcards

Volume 5 Flashcards

1
Q

(801) How much sensible heat is added if the temperature of air increases from 70 to 80 °F?
a. 5 °F.
b. 10 °F.
c. 15 °F.
d. 70 °F.

A

b. 10 °F.

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2
Q

(801) What occurs during the latent heat of condensation?
a. Refrigerant gas solidifies.
b. Vapor turns to a liquid.
c. Liquid turns to a vapor.
d. Liquid turns to a gas.

A

b. Vapor turns to a liquid.

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3
Q

(801) What determines the pressure required to achieve a specific flow rate?
a. Pump design.
b. Ambient temperatures.
c. Pressure enthalpy charts.
d. Design of the piping system.

A

d. Design of the piping system.

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4
Q

(802) What three processes take place in the condenser?
a. Superheating, boiling, and subcooling.
b. Desuperheating, boiling, and subcooling.
c. Superheating, condensing, and subcooling.
d. Desuperheating, condensing, and subcooling.

A

d. Desuperheating, condensing, and subcooling.

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5
Q

(802) The heat being absorbed in the evaporator comes from the
a. product being cooled or the conditioned space.
b. compressor discharge.
c. condenser.
d. receiver.

A

a. product being cooled or the conditioned space.

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6
Q

(803) What happens to the exhaust valve of a compressor during the intake stroke?
a. Backpressure from the low side opens it.
b. Backpressure from the high side opens it.
c. Backpressure from the high side closes it.
d. Frontpressure from the high side closes it.

A

c. Backpressure from the high side closes it.

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7
Q

(803) What effect do fins on the shell of a compressor have?
a. Decrease surface area and allow more heat transfer with return air.
b. Increase surface area and allow more heat transfer with supply air.
c. Increase surface area and allow more heat transfer with ambient air.
d. Decrease surface area and allow more heat transfer with ambient air.

A

c. Increase surface area and allow more heat transfer with ambient air.

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8
Q

(803) What does a check valve in the discharge line prevent with a rotary compressor?
a. Liquid accumulation.
b. Gas leaking back to the condenser.
c. Liquid condensing in the compressor.
d. Gas from leaking back to compressor.

A

d. Gas from leaking back to compressor.

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9
Q

(803) Why must you be careful when placing meter leads on compressor terminals?
a. Compressor terminals also act as refrigerant access ports.
b. Expansion device could open rapidly and cause a blowout.
c. This is the weakest section of the compressor and a blowout could occur.
d. This is the strongest section of the compressor but damage could still occur.

A

c. This is the weakest section of the compressor and a blowout could occur.

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10
Q

(803) What is the result of a loose electrical connection at the compressor terminal?
a. Increased heat.
b. Decreased heat.
c. Better conductivity.
d. Decreased resistance.

A

a. Increased heat.

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11
Q

(803) Where are internal motor protection devices embedded?
a. In the discharge line.
b. On the compressor shell.
c. In the hot suction gas line.
d. In or near the motor windings.

A

d. In or near the motor windings.

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12
Q

(804) Desuperheating generally takes place in the
a. liquid line and first few coils of the condenser.
b. suction line and first few coils of the evaporator.
c. discharge line and last few coils of the condenser.
d. discharge line and first few coils of the condenser.

A

d. discharge line and first few coils of the condenser.

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13
Q

(804) Non-condensables inside a refrigeration system are in what form?
a. Gas.
b. Solid.
c. Liquid.
d. Non-condensables do not exist in a system.

A

a. Gas.

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14
Q

(804) In a refrigeration system air gets trapped at the
a. top of the condenser and receiver.
b. bottom of the condenser and receiver.
c. top of the condenser and accumulator.
d. bottom of the evaporator and receiver.

A

a. top of the condenser and receiver.

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15
Q

(804) What effect does counter flow have in a double-tube condenser?
a. Creates fluid flow issues.
b. Gives condenser a lower efficiency.
c. Gives condenser a higher efficiency.
d. Counter flow decreases flow because of counter-resistance.

A

c. Gives condenser a higher efficiency.

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16
Q

(805) What is the relationship between a capillary tube metering device and refrigerant charge?
a. The charge is less critical.
b. Using a capillary device makes the charge critical.
c. Capillary tube will not meter refrigerant if the charge is too high.
d. Capillary tube maintains constant superheat so the charge is not as important.

A

b. Using a capillary device makes the charge critical.

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17
Q

(805) A filter strainer should be installed at the inlet of the capillary tube to
a. prevent dirt and foreign matter from clogging the tube.
b. create 40% flash gas for the evaporator.
c. create the designed pressure drop.
d. pre-flash the liquid refrigerant.

A

a. prevent dirt and foreign matter from clogging the tube.

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18
Q

(805) When the evaporator pressure rises after the compressor stops the automatic expansion valve (AXV)?
a. opens.
b. closes.
c. opens 60%.
d. trips out the compressor control.

A

b. closes.

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19
Q

(805) What happens when a stepper motor expansion device receives a signal from the controller?
a. It shuts the system down.
b. Rotates a precise, small amount.
c. It creates a 50% flash gas condition.
d. Rotates inaccurately and in a large amount.

A

b. Rotates a precise, small amount.

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20
Q

(805) An electronic expansion valve stepper motor’s electronic controller receives a pressure reading from a
a. transducer in the liquid line.
b. transducer in the suction line.
c. thermistor placed on the liquid line.
d. thermistor placed on the compressor discharge.

A

b. transducer in the suction line.

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21
Q

(805) How does a pulse width modulating electronic expansion valve (EEV) vary refrigerant flow?
a. A signal quickly opens and slowly closes the solenoid valve.
b. A signal slowly opens and quickly closes the check valve.
c. A signal quickly opens and closes the solenoid valve.
d. A signal slowly opens and closes the check valve.

A

c. A signal quickly opens and closes the solenoid valve.

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22
Q

(806) In an indirect expansion system the coil containing the secondary refrigerant is
a. in an air handler.
b. in the primary control loop.
c. inside offices to reject heat.
d. located outside to reject heat.

A

a. in an air handler.

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23
Q

(806) Dirt on an evaporator coil acts like
a. another fin.
b. a conductor.
c. an insulator.
d. increased surface area.

A

c. an insulator.

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24
Q

(806) In a system using a capillary tube how does very little heat being absorbed affect superheat?
a. There will be negative superheat.
b. There will be too much superheat.
c. There will be little or no superheat.
d. Superheat is kept constant by the capillary tube.

A

c. There will be little or no superheat.

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25
Q

(807) Chlorofluorocarbon refrigerants are “doomed” because they
a. contain sulfate.
b. contain chlorine.
c. contain chloroxide.
d. are not very efficient.

A

b. contain chlorine.

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26
Q

(807) A low flow of refrigerant affects oil return to the compressor by causing
a. the refrigerant to lie on bottom of tubing.
b. too much refrigerant to return to compressor.
c. too much oil to return to compressor and flood it.
d. oil to lie on the bottom of the refrigeration tubing.

A

d. oil to lie on the bottom of the refrigeration tubing.

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27
Q

(808) What effect does friction have on the temperature of moving parts in an air conditioning (A/C) system?
a. Increases temperature.
b. Decreases temperature.
c. Maintains constant temperatures.
d. Oil prevents friction and has no effect on temperature.

A

a. Increases temperature.

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28
Q

(808) How is oil forced to the main bearings when the pressure lubrication method is used?
a. Splashing.
b. Crank throw.
c. Passive force.
d. A small oil pump.

A

d. A small oil pump.

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29
Q

(809) What affects the resistance of a thermistor?
a. Weight.
b. Pressure.
c. Temperature.
d. Absolute pressure.

A

c. Temperature.

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30
Q

(810) Low voltage thermostats directly operate
a. compressors.
b. electric heaters.
c. solenoids, relays, and contactors.
d. compressors and electric heaters.

A

c. solenoids, relays, and contactors.

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31
Q

(810) What effect does an improper location of a thermostat have on the temperature being sensed?
a. It senses the wrong pressure.
b. It senses the wrong temperature.
c. Proper control of space temperature.
d. It senses ambient pressures with more sensitivity.

A

b. It senses the wrong temperature.

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32
Q

(811) What is the relationship between a liquid receiver and a system’s refrigerant charge?
a. Liquid receivers are too small to hold the complete system’s charge.
b. Liquid receivers are large enough to hold 50% of the system’s charge.
c. Liquid receivers are large enough to hold 75% of the system’s charge.
d. Liquid receivers are large enough to hold the complete system’s charge.

A

d. Liquid receivers are large enough to hold the complete system’s charge.

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33
Q

(811) What effect does a muffler have on a domestic refrigeration system’s noise?
a. Increases the noise level.
b. It breaks up the pressure pulses.
c. It creates pressure pulses for quiet operation.
d. None, mufflers cannot be used on refrigeration systems.

A

b. It breaks up the pressure pulses.

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34
Q

(811) Insulating an oil separator prevents the refrigerant
a. liquid from vaporizing and returning to the condenser as a liquid.
b. liquid from vaporizing and returning to the compressor as a vapor.
c. vapor from condensing and returning to the evaporator as a liquid.
d. vapor from condensing and returning to the compressor as a liquid.

A

d. vapor from condensing and returning to the compressor as a liquid.

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35
Q

(811) Filter-driers are usually installed on the high-side between the
a. evaporator and compressor.
b. oil separator and compressor.
c. expansion valve and evaporator.
d. receiver and the expansion valve.

A

d. receiver and the expansion valve.

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36
Q

(812) How do compressors with inverters vary the output capacity of the compressor?
a. By using an inverter.
b. With cylinder unloaders.
c. With constant speed devices.
d. By using light emitting diodes.

A

a. By using an inverter.

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37
Q

(812) What allows the technician to adjust variable frequency drive (VFD) parameters via a laptop?
a. Software.
b. Stepper motors.
c. WiFi connection.
d. Pulse width modulation.

A

a. Software.

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38
Q

(812) Using the control strategy table from page 2–37, what frequency is being produced at step 10?
a. 140 hertz
b. 150 hertz.
c. 160 hertz.
d. 170 hertz.

A

b. 150 hertz.

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39
Q

(812) According to the control strategy table on page 2–38, what is the output of the inverter compressor at step 16?
a. 20 hertz.
b. 60 hertz.
c. 70 hertz.
d. 80 hertz.

A

b. 60 hertz.

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40
Q

(812) What is the end result of the solenoid valve closing on a compressor with an internal unloader?
a. Intake valve held open.
b. Intake valve held closed.
c. Exhaust valve held open.
d. Exhaust valve held closed.

A

a. Intake valve held open.

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41
Q

(812) How is discharge from one or more cylinders allowed to flow through a bypass line and into the suction line on a compressor with external unloaders and gas bypass?
a. Evaporator valve opens.
b. A solenoid valve opens.
c. A solenoid valve closes.
d. Thermostatic expansion valve (TXV) closes.

A

b. A solenoid valve opens.

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42
Q

(813) Which of the following is not a method of condenser capacity control?
a. Cycling compressor on and off.
b. Modulating water flow rates.
c. Cycling fans on and off.
d. Modulating fan speed.

A

a. Cycling compressor on and off.

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43
Q

(813) Condenser flooding is necessary on cooler or cold days to
a. maintain constant superheat.
b. maintain constant head pressure.
c. starve the evaporator to increase superheat.
d. maintain constant evaporator saturation temperatures.

A

b. maintain constant head pressure.

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44
Q

(813) What is the relationship between condenser flooding and the metering device?
a. Flooding is required to supply 30% vapor to metering device.
b. Flooding ensures the metering device is receiving 70 percent vapor.
c. Flooding ensures the metering device is receiving a constant liquid pressure.
d. Flooding ensures refrigerant flashes off immediately before metering device.

A

c. Flooding ensures the metering device is receiving a constant liquid pressure.

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45
Q

(813) What does the three-way solenoid react to in a system that uses condenser splitting?
a. Suction pressure.
b. Indoor dry-bulb temperatures.
c. Indoor wet-bulb temperatures.
d. Either outside ambient conditions or head pressure.

A

d. Either outside ambient conditions or head pressure.

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46
Q

(813) On a condenser splitting capacity control system, a three-way solenoid valve sends refrigerant to both condensers during warmer weather conditions because the refrigerant needs
a. more space to sustain proper head pressures and absorb heat.
b. more space to sustain proper head pressures and reject heat.
c. less space to sustain proper head pressures and absorb heat.
d. less space to sustain proper head pressures and reject heat.

A

b. more space to sustain proper head pressures and reject heat.

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47
Q

(813) When airflow is used to control condenser capacity what effect does decreasing fan speed have?
a. Reduces capacity.
b. Increases capacity.
c. Stops flow in the condenser.
d. Increases flow in the condenser.

A

a. Reduces capacity.

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48
Q

(813) What effect does closing air dampers have on condenser capacity?
a. Reduces capacity.
b. Increases capacity.
c. Increases capacity over 120 percent.
d. Stops flow in condenser coils.

A

a. Reduces capacity.

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49
Q

(814) What happens every 6 hours when a simple timed defrost system is set for an interval of 6 hours?
a. Defrost is terminated.
b. Defrost heaters are de-energized.
c. Defrost initiated only when needed.
d. Defrost is initiated even if it is not needed.

A

d. Defrost is initiated even if it is not needed.

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50
Q

(814) Why do the compressor and evaporator fan not run during defrost?
a. The evaporator fan would freeze.
b. The system should not be producing a cooling effect.
c. The compressor would increase temperature too much.
d. Compressor would burst the evaporator because of extra pressure.

A

b. The system should not be producing a cooling effect.

51
Q

(814) When does a time initiated, pressure-terminated defrost timer turn off defrost?
a. When discharge pressure corresponds to the temperature the ice would have melted.
b. When condenser pressure corresponds to the temperature the ice would have melted.
c. When liquid line pressure corresponds to the temperature the ice would have melted.
d. When evaporator pressure corresponds to the temperature the ice would have melted.

A

d. When evaporator pressure corresponds to the temperature the ice would have melted.

52
Q

(815) On a single temperature, multiple evaporator system the needs of each evaporator are controlled by a
a. high temperature control.
b. low pressure motor control.
c. high pressure motor control.
d. liquid line, low pressure control.

A

b. low pressure motor control.

53
Q

(815) Where are evaporator pressure regulator (EPR) valves placed in a multiple temperature, multiple evaporator system?
a. In the liquid line.
b. In the discharge line.
c. In the suction line of the warmer evaporator.
d. Immediately after the metering device, before the evaporator.

A

c. In the suction line of the warmer evaporator.

54
Q

(816) What is a result of a clogged window unit’s drip pan?
a. Condensate leak.
b. Decreased humidity.
c. Increased system efficiency.
d. Evaporator fan shut down and an alarm sounds.

A

a. Condensate leak.

55
Q

(816) What is the relationship between a rooftop unit and its refrigerant charge as it is shipped to the job site?
a. Roof top units need refrigerant added to account for added line sets.
b. Roof top units come empty and need to be charged.
c. All roof top units used chilled water to cool.
d. Roof top units come factory-charged.

A

d. Roof top units come factory-charged.

56
Q

(816) When ambient temperatures are low what does the economizer on a roof top unit do with outside air?
a. It uses it to heat the space.
b. It shuts off outside air 100%.
c. It uses only return air to cool the space.
d. It uses the outside air to cool the space.

A

d. It uses the outside air to cool the space.

57
Q

(816) Using the outside air to cool a space is called “free cooling” because
a. no mechanical components are operating.
b. it bypasses the heating and cooling systems.
c. it costs no money to cool the already cool outside air.
d. outside is easier to move due to lower static pressures.

A

c. it costs no money to cool the already cool outside air.

58
Q

(817) When a heat pump is in heat mode, heat transfers from the outdoor air to the outdoor coil because the
a. outdoor coil is warmer than the outdoor air.
b. outdoor coil is colder than the outdoor air.
c. indoor coil is colder than the outdoor coil.
d. indoor coil is colder than the outdoor air.

A

b. outdoor coil is colder than the outdoor air.

59
Q

(817) What is used to control the resistive heaters used with a heat pump?
a. Either a single-stage cooling or two-stage heating thermostat.
b. Thermostatic expansion valve (TXV).
c. Solenoid valves.
d. Aquastats.

A

a. Either a single-stage cooling or two-stage heating thermostat.

60
Q

(817) Where do the reversing valve’s capillary lines at both ends of the cylinder of connect?
a. Suction line.
b. Pilot solenoid chamber.
c. The port going to the compressor.
d. The port going to the outdoor coil.

A

b. Pilot solenoid chamber.

61
Q

(817) When does the reversing valve’s pilot solenoid pin carrier change position?
a. This pin does not move.
b. During shutdown mode.
c. When the compressor is off.
d. When the solenoid coil is energized or de-energized.

A

d. When the solenoid coil is energized or de-energized.

62
Q

(817) When both a thermostatic expansion valve (TXV) and a capillary tube are installed on a heat pump system, the TXV is used in a heat pump’s winter operation because
a. it can fluctuate the subcooling.
b. it maintains constant subcooling.
c. winter conditions are less constant.
d. winter conditions are more constant.

A

c. winter conditions are less constant.

63
Q

(817) How do heat pump compressors handle some liquid slugging?
a. By using smaller valves.
b. Through the liquid slug port.
c. Through the accumulator slugging port.
d. Using stronger internal valves and components.

A

d. Using stronger internal valves and components.

64
Q

(817) What is the relationship between the outdoor fan’s current draw during defrost and ice buildup on the outdoor coil?
a. More ice buildup means a higher current draw.
b. More ice buildup means a lower current draw.
c. Zero ice buildup means too much amperage.
d. Small ice buildup means amps are too low.

A

a. More ice buildup means a higher current draw.

65
Q

(818) During a pre-operational inspection all electrical connections are checked
a. for 120 volts.
b. to ensure they are discolored.
c. to ensure they have overheated.
d. for looseness, corrosion, discoloration, or other signs of overheating.

A

d. for looseness, corrosion, discoloration, or other signs of overheating.

66
Q

(818) What is checked for cleanliness during a pre-operational inspection?
a. Only mechanical devices.
b. Only electrical devices.
c. The unit as a whole.
d. Only your truck.

A

c. The unit as a whole.

67
Q

(818) A spot of oil is a good indication of
a. a leak.
b. clean tubing.
c. a leak free system.
d. good oil flow through system.

A

a. a leak.

68
Q

(819) During an operational test what step is performed after you ensure proper power? a. Turn off the breaker.
b. Turn evaporator fan off.
c. Turn the compressor off.
d. Amperage checks on motors.

A

d. Amperage checks on motors.

69
Q

(819) What must be accounted for when using the pressure-temperature chart for an azeotropic refrigerant?
a. Temperature glide.
b. Only one refrigerant is used.
c. The same saturation temperatures throughout the system.
d. The same boiling temperatures throughout the evaporator.

A

a. Temperature glide.

70
Q

(819) An assumption when reading pressure on the suction service valve with gauges is the pressure read at the suction service valve of the compressor is the same pressure at the
a. outlet of the evaporator.
b. outlet of the condenser.
c. inlet of the evaporator.
d. inlet of the condenser.

A

a. outlet of the evaporator.

71
Q

(819) When trying to detect non-condensables what is the next step after isolating the condenser?
a. Read condenser pressure.
b. Run the system fully loaded.
c. Let condenser settle and reach ambient temperature.
d. Compare the proper pressure with the measured pressure.

A

c. Let condenser settle and reach ambient temperature.

72
Q

(819) When adding oil to a system what is the next step after closing the suction shut-off?
a. Replace the oil fill plug.
b. Run the compressor fully loaded.
c. Stop the compressor and isolate it by closing discharge valve.
d. Stop the compressor and isolate it by closing the suction valve.

A

c. Stop the compressor and isolate it by closing discharge valve.

73
Q

(819) What is the final step when adding oil to a system?
a. Shut the compressor off.
b. Slowly remove the oil fill plug.
c. Remove the oil fill plug slowly.
d. Replace oil fill plug, run the compressor, and recheck oil.

A

d. Replace oil fill plug, run the compressor, and recheck oil.

74
Q

(820) Why should outdoor equipment in locations on the ocean’s coast be serviced more frequently?
a. Because of the sand in contactors.
b. Because of the sand buildup on the coils.
c. Ocean salt is airborne and is highly corrosive.
d. Equipment on the coast has shorter manufacturer specified maintenance intervals.

A

c. Ocean salt is airborne and is highly corrosive.

75
Q

(821) How could an inexperienced technician best locate various chiller components?
a. Troubleshooting flow charts.
b. Manufacturer’s diagrams.
c. Asking a coworker.
d. Guesswork.

A

b. Manufacturer’s diagrams.

76
Q

(821) How are chilled water pumps controlled?
a. Through laptops.
b. Chiller controller.
c. Antifreeze sensors.
d. Cooling tower sensors.

A

b. Chiller controller.

77
Q

(821) On a centrifugal chiller system before entering the second stage impeller the vapors from the first-stage impeller mix with flash gas vapors from the
a. condenser.
b. evaporator.
c. economizer.
d. compressor’s third stage.

A

c. economizer.

78
Q

(821) Refrigerant is added on a centrifugal chiller system through a charging valve on the side of the
a. cooling tower.
b. compressor.
c. condenser.
d. cooler.

A

d. cooler.

79
Q

(821) What is the probable cause of large amounts of water collected by a centrifugal chiller’s purge unit?
a. Leaky tubes.
b. Good heat transfer.
c. Water in the system is too hot and needs to be purged.
d. Purge unit malfunction because it is supposed to remove air only.

A

a. Leaky tubes.

80
Q

(822) Water in a closed-loop design geothermal heat pump that uses a well is discharged
a. at the top of the well.
b. at the bottom of the well.
c. in the middle of the well.
d. at least 50 feet from the well.

A

b. at the bottom of the well.

81
Q

(823) How is the pressure plotted on the pressure enthalpy (PE) chart?
a. From top to bottom.
b. From bottom to top.
c. In pounds per square inch gauge (psig).
d. In pounds per square inch absolute (psia).

A

d. In pounds per square inch absolute (psia).

82
Q

(823) At sea level, what is the absolute pressure if the gauge reads 20 pressure per square inch gauge (psig)?
a. 34.7 pressure per square inch absolute (psia).
b. 44.7 psia.
c. 55.7 psia.
d. 66.7 psia.

A

a. 34.7 pressure per square inch absolute (psia).

83
Q

(823) The pressure enthalpy (PE) chart is based on how many pounds of refrigerant?
a. 1.
b. 2.
c. 10.
d. 100.

A

a. 1.

84
Q

(823) On the pressure enthalpy (PE) chart a change in state takes place
a. inside the curve.
b. to the left of the curve.
c. to the right of the curve.
d. in the area above the curve.

A

a. inside the curve.

85
Q

(823) What is the condition of refrigerant on pressure enthalpy (PE) chart if the plot is on the right side of the curve?
a. Saturated vapor.
b. Saturated liquid.
c. Subcooled liquid.
d. Superheated vapor.

A

a. Saturated vapor.

86
Q

(824) How many readings must be taken to fill out the pressure enthalpy (PE) chart?
a. 3.
b. 7.
c. 9.
d. 19.

A

b. 7.

87
Q

(824) According to figure 4–5, where is the control point of the thermal bulb plotted?
a. H.
b. G.
c. D.
d. A.

A

b. G.

88
Q

(824) According to figure 4–5, the evaporator superheat is located between what two points?
a. H to A.
b. G to H.
c. F to G.
d. C to D.

A

c. F to G.

89
Q

(824) According to figure 4–5, the subcooling in the liquid line is located between what two points?
a. C to D.
b. F to G.
c. G to H.
d. H to A.

A

a. C to D.

90
Q

(824) According to figure 4–5, where is the flash gas located?
a. From A to V.
b. From F to G.
c. Where line F stops when it goes horizontally.
d. Where line E stops when it goes vertically downward.

A

d. Where line E stops when it goes vertically downward.

91
Q

(824) How are pressure enthalpy (PE) charts filled out if paper charts are not used?
a. Graph paper.
b. Chalkboard.
c. Software.
d. By hand.

A

c. Software.

92
Q

(825) How long should the system be allowed to run before measuring superheat?
a. 2 to 3 seconds.
b. 36 hours.
c. 2 weeks.
d. Long enough for temperature and pressure to stabilize.

A

d. Long enough for temperature and pressure to stabilize.

93
Q

(825) What is the next step for temperature readings after cleaning the pipe?
a. Let system stabilize.
b. Verify proper airflow.
c. Take condenser inlet temperature.
d. Take temperature at the outlet of the evaporator.

A

d. Take temperature at the outlet of the evaporator.

94
Q

(825) What step is performed after converting the pressure reading to temperature?
a. Add saturation temperature from the suction line temperature.
b. Add saturation temperature from the discharge line temperature.
c. Subtract saturation temperature from the liquid line temperature.
d. Subtract saturation temperature from the suction line temperature.

A

d. Subtract saturation temperature from the suction line temperature.

95
Q

(825) What is determined before adjusting a thermostatic expansion valve (TXV) superheat?
a. The rest of the system is functioning properly.
b. Capillary tube length.
c. Compressor size.
d. Coil size.

A

a. The rest of the system is functioning properly.

96
Q

(825) What direction is the thermostatic expansion valve (TXV) adjustment screw turned to decrease superheat?
a. Counterclockwise.
b. Back and forth.
c. Up and down.
d. Clockwise.

A

a. Counterclockwise.

97
Q

(825) Assuming everything else is working properly how is superheat decreased on a system with a capillary tube?
a. Add refrigerant.
b. Remove refrigerant.
c. Block 50 percent of condenser coil.
d. Block 50 percent of evaporator coil.

A

a. Add refrigerant.

98
Q

(826) How long should a system run before measuring subcooling?
a. 2 to 3 seconds.
b. 2 to 3 days.
c. At least 3 weeks.
d. Until temperature and pressure stabilize.

A

d. Until temperature and pressure stabilize.

99
Q

(826) When measuring subcooling the next step after measuring pressure at the liquid line is to
a. measure pressure at the suction line.
b. measure temperature at the liquid line.
c. measure pressure reading at the subcooling point.
d. convert the pressure reading to temperature using the pressure-temperature chart.

A

d. convert the pressure reading to temperature using the pressure-temperature chart.

100
Q

(826) Where is the high-side hose connected when using digital gauges to measure subcooling?
a. Condenser inlet service port.
b. Discharge line service port.
c. Suction line service port.
d. Liquid line service port.

A

d. Liquid line service port.

101
Q

(826) What step is performed after adding refrigerant to decrease subcooling?
a. Turn on system.
b. Let system stabilize.
c. Read new superheat.
d. Remove more refrigerant.

A

b. Let system stabilize.

102
Q

(827) What is the first step when topping off a system with vapor?
a. Zero the scale.
b. Purge the hoses.
c. Start compressor.
d. Determine proper amount of refrigerant required by measuring superheat or subcooling.

A

d. Determine proper amount of refrigerant required by measuring superheat or subcooling.

103
Q

(827) After connecting the manifold gauge assembly (MGA) and hoses, what position are the service valves placed when topping off a system with vapor?
a. Front seated.
b. Back seated.
c. Mid-position.
d. Front seat the compressor discharge.

A

c. Mid-position.

104
Q

(827) After the proper amount of superheat has been determined from a chart you measure
a. indoor wet bulb.
b. outdoor dry bulb.
c. relative humidity.
d. the total superheat and compare it to the amount needed.

A

d. the total superheat and compare it to the amount needed.

105
Q

(828) What step is performed before opening the high- and low-side valves during passive recovery not using the compressor?
a. Tap compressor.
b. Heat the compressor.
c. Place recovery device in ice bath.
d. Open high-side manifold gauge assembly (MGA) valve.

A

c. Place recovery device in ice bath.

106
Q

(828) What is placed between the manifold gauge assembly (MGA) center port and recovery machine?
a. In-line filter drier.
b. High side valve.
c. Schrader valve.
d. Vacuum pump.

A

a. In-line filter drier.

107
Q

(828) What is the first step when performing a triple evacuation?
a. Remove cores.
b. Turn on the vacuum pump.
c. Gather larger and shorter hoses.
d. Gather smaller and longer hoses.

A

c. Gather larger and shorter hoses.

108
Q

(828) When performing a triple evacuation how deep of a vacuum should be pulled the first time?
a. 2 pressure per square inch gauge (psig).
b. 6000 microns.
c. 1500 microns.
d. 6 psig.

A

c. 1500 microns.

109
Q

(828) During a triple evacuation how much pressure is put into a system after the cylinder valves are opened?
a. .001 to .01 pressure per square inch gauge (psig).
b. 0 to 3 psig.
c. 100 to 250 microns.
d. 1500 microns.

A

b. 0 to 3 psig.

110
Q

(829) Pump down is performed to
a. change out the receiver.
b. remove the condenser coil.
c. remove the liquid line filter-drier.
d. make repairs to the low-side components.

A

d. make repairs to the low-side components.

111
Q

(829) When pumping down a system what step is performed after the unit cycles off?
a. Front seat the discharge service valve.
b. Remove the expansion device.
c. Find the liquid line receiver.
d. Front seat the King valve.

A

d. Front seat the King valve.

112
Q

(829) When performing a condenser pump down what step is performed after the gauge reaches 0 pressure per square inch gauge (psig)?
a. Back seat the liquid service valve.
b. Front seat the suction service valve.
c. Back seat the suction service valve.
d. Front seat the liquid line service valve.

A

b. Front seat the suction service valve.

113
Q

(830) What does the TRICON Refrigerated Container System (TRCS) explosion icon indicate?
a. Material is made to withstand mortar attacks.
b. Extreme cold conditions may cause frostbite.
c. Material can explode if subjected to high temperatures.
d. Poor fire conditions exist and the system could explode.

A

c. Material can explode if subjected to high temperatures.

114
Q

(830) If the ball float on the TRICON Refrigerated Container System (TRCS) is floating what effect does it have drainage?
a. Allows liquid to escape.
b. Prevents liquid from escaping.
c. As the ball drops, so does the pressure.
d. Heats the condensation to allow vapor to escape.

A

a. Allows liquid to escape.

115
Q

(830) What is the purpose of item 1 in figure 5–6?
a. Protects inside product from enemy sights.
b. Allows operation of unit with doors closed.
c. Protects inside product during black out procedures.
d. Allows operation of unit with the doors open and maintain refrigeration.

A

d. Allows operation of unit with the doors open and maintain refrigeration.

116
Q

(830) Why is item 3 in figure 5–12 provided?
a. To access evaporator pressure.
b. To access evaporator temperature.
c. To allow quick release of entire charge of refrigerant.
d. Measure pressure, recover, charge, and purge refrigerant.

A

d. Measure pressure, recover, charge, and purge refrigerant.

117
Q

(831) What is indicated if a TRICON Refrigerated Container System (TRCS) wire marking starts with a 6?
a. The wire is high voltage, 2 volts DC positive power.
b. The wire is low voltage, 2 volts DC negative power.
c. The wire is low voltage, 12 volts DC positive power.
d. The wire is high voltage, 12 volts DC negative power.

A

c. The wire is low voltage, 12 volts DC positive power.

118
Q

(831) What does TRICON Refrigerated Container System (TRCS) relay 1U1K2 power?
a. The compressor.
b. 1 evaporator fan.
c. 3 evaporator fans.
d. 4 condenser fans.

A

c. 3 evaporator fans.

119
Q

(831) What it the relationship between the TRICON Refrigerated Container System (TRCS) thermal control switch (1S5) and the daytime and nighttime temperatures?
a. The switch increases system usage during the day.
b. The switch limits operation of the evaporator fan only.
c. The switch runs the condenser fan only during the day.
d. The switch takes advantage of the difference in daytime and nighttime temperatures.

A

d. The switch takes advantage of the difference in daytime and nighttime temperatures.

120
Q

(832) How can a technician determine if the Field Deployable Environmental Control Unit (FDECU) crankcase heater is energized?
a. Touch the compressor suction line.
b. Touch the compressor discharge line.
c. The fault 3E1 will read on the display.
d. A compressor warm-up indicator light on the control panel.

A

d. A compressor warm-up indicator light on the control panel.

121
Q

(832) What is the relationship between the Field Deployable Environmental Control Unit (FDECU)–2 and compressor crankcase heaters and lights?
a. It has two crankcase heaters that illuminate.
b. It does not have a crankcase heater or light.
c. It has one low amperage heater that is off during operation.
d. It has two low amperage/volt heaters that are off during operation.

A

a. It has two crankcase heaters that illuminate.

122
Q

(833) How does the Field Deployable Environmental Control Unit (FDECU) inside check valve affect refrigerant flow in cooling mode?
a. Sends the cool refrigerant to the outdoor coil.
b. Sends the hot refrigerant to the indoor coil.
c. Allows flow to all components.
d. Does not allow flow.

A

d. Does not allow flow.

123
Q

(833) How is the Field Deployable Environmental Control Unit (FDECU)–5 ability to shut down the compressor and condenser fan based on outside air updated from 18 to 28 °F?
a. Using Keco Industries field adjustment procedure 4.
b. Using Keco Industries field adjustment procedure 5595.
c. Using Messineo Industries field adjustment procedure 54.
d. Using Messineo Industries field adjustment procedure 5590.

A

b. Using Keco Industries field adjustment procedure 5595.

HVAC CDC's (5 decks)

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