Term
| Hermetic Compressors are cooled by? |
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Definition
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Term
Radiant heat travels...?
A. as a fluid to a sink
B. Through latent to sensible heat change
C. molecule to molecule
D. In a wave form |
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Definition
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Term
The compound gauge reads?
A. Atmospheric and absolute pressure
B. Above and below atmospheric pressure
C. Only above PSIA
D. Conventional pressure |
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Definition
| B. Above and Below atmospheric pressure |
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Term
The high side pressure gauge reads?
A. PSIA
B. above and below atmospheric pressure
C. Superheat
D. Above Atmospheric pressure |
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Definition
| D. Above Atmospheric pressure |
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Term
Latent heat changes?
A. sensible temperatures
B. requires a source and a sink
C. changes the state of a substance
D. Is read at sea level |
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Definition
| C. changes the state of a substance |
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Term
Convection heat transfer is?
A. the transfer of heat thru fluid
B. friction induced heat
C. molecule to molecule
D. in wave form |
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Definition
| A. The transfer of heat thru a fluid |
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Term
Capillary metering devices are charged using?
A. sub-cooling
B. sensible heat
C. superheat
D. saturation temperature |
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Definition
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Term
Changing the temperature and _______ can change the boiling point of a liquid
A. state of change
B. pressure
C. sensible thermal energy
D. heat |
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Definition
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Term
A vacuum is read in?
A. feet of HG
B. 14.7 PSI
C. PSIA
D. Inches of mercury |
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Definition
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Term
A perfect system evacuation will read as?
A. 500 microns
B. 14.7 PSI
C. 29.9 HG
D. 0 PSIA |
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Definition
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Term
Conduction transfers heat by?
A. fluid heat transfer
B. natural draft
C. closely packed molecules in contact with one another
D. In a wave form |
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Definition
| C. Closely packed molecules in contact with one another |
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Term
Barometric and atmospheric pressures are?
A. condensation pressures
B. are measured in BTU's
C. opposite
D. The same pressure |
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Definition
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Term
A screw compressor use's?
A. centrifugal force
B. auger screws to compress gas
C. is a passive device
D. compresses liquid refrigerant to the condenser |
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Definition
| B. Auger screws to compress gas |
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Term
Manometer measures pressures in?
A. inches of water column
B. PSIG
C. absolute
D. atmospheric |
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Definition
| A. Inches of water column |
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Term
Sensible heat can be measured in?
A. wet bulb
B. dew point
C. Fahrenheit
D. the change of state of liquid to vapor |
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Definition
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Term
Too much moisture in the system can cause?
A. increased circulation of the refrigerant
B. the moisture to migrate from the liquid line dryer and freeze up the TXV
C. Decrease TXV bulb pressure
D. Both A & C |
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Definition
| B. The moisture to migrate from the liquid line dryer and freeze up the TXV |
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Term
An over charged fixed metering device will have?
A. low superheat
B. high superheat
C. normal superheat
D. no change because the liquid receiver accommodates for excess system liquid |
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Definition
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Term
Adding fins to an evaporator will?
A. protect the evaporator tubing
B. directs the air flow better, but does not change the heat transfer rate
C. increases the heat transfer by increasing the surface area
D. decrease system capacity |
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Definition
| C. Increases the heat transfer by increasing the surface area |
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Term
What type of compressor is field serviceable.
A. rotary
B. semi-hermetic
C. hermetic
D. All of the above |
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Definition
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Term
The Evaporator?
A. removes only sensible heat
B. removes latent heat to a sensible heat change
C. absorbs large amounts of heat
D. humidifies the air |
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Definition
| C. Absorbs large amounts of heat |
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Term
What is the normal evaporator refrigerant saturation temperature?
A. 50*F
B. 45*F
C. 5*F
D. 40*F |
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Definition
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Term
What is the normal evaporator split?
A. 30*F
B. 20*C
C. 20*F
D. 40*F |
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Definition
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Term
What is the normal condenser split?
A. 45*F
B. 10*F
C. 5*F
D. 30*F |
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Definition
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Term
An evaporator superheat should be?
A. 10*F
B. 5*F
C. 20*F
D. 40+F |
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Definition
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Term
The condenser refrigerant saturated @ 125*F and the liquid line temperature is @ 120*F what is the sub cooling?
A. 10*F
B. 5*C
C. -5*F
D. 5*F |
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Definition
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Term
A TXV undercharge will have?
A. high superheat and high sub-cool
B. low superheat and high sub-cool
C. high superheat and low sub-cool
D. low superheat and low sub-cool |
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Definition
| C. High superheat and low sub-cool |
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Term
The purpose of the condenser coil is to reject heat?
A. true
B. false |
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Definition
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Term
| If the technician dose not purge their gauges what will happen? |
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Definition
| Air and non condensbles will be added to the system. |
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Term
| A system that does not use fans or pumps is known as? |
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Definition
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Term
| A system that uses pumps and fans for heat transfer is known as? |
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Definition
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Term
Thermostatic expansion valves operate under varying conditions and operates on __________?
A. saturation pressure @the suction line
B. superheat on the suction line
C. sub-cooling on the liquid line
D. sensible heat @ the suction line |
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Definition
| B. Superheat on the suction line |
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Term
What two components control the pressures in the system?
A. heat from the evaporator and the TXV
B. suction accumulator and liquid receiver
C. compressor and metering device
D. compressor and sub-cooling |
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Definition
| C. Compressor and metering device |
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Term
What is the perfect absolute vacuum?
A. 0 PSI absolute
B. 14.7 PSIA
C. 0" HG absolute
D. 29.9" HG |
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Definition
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Term
Humid air is heaver then dry air?
A. true
B. false |
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Definition
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Term
Before a technician can open up the system to atmospheric pressure for repair of major components they must first?
A. recover the systems oil
B. replace all the shrader core valves
C. pull a vacuum of 29"hg
D. recover the refrigerant |
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Definition
| D. Recover the refrigerant |
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Term
A hermetic compressor that uses stationary and a moving scroll is called?
A. chiller compressor
B. rotary compressor
C. scroll compressor
D. screw compressor |
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Definition
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Term
What type of compressor uses rolling piston?
A. rotary
B. screw
C. reciprocating
D. centrifugal |
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Definition
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Term
At sea level 0 psig is equal to ______ psia.....
A. 30"HG
B. -15
C. 0
D. 14.7 |
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Definition
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Term
Metals that are good electrical conductors?
A. are also good absorbers of any vibrations in the system
B. are not generally used in higher seer units
C. are also good for their quick heat transfer quality's
D. are also bad for thermal energy conduction |
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Definition
| C. Are also good for their quick heat transfer quality's |
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Term
| A natural convection system is also called? |
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Definition
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Term
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Definition
| Less then atmospheric pressure |
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Term
What is bulb pressure?
A. bulb pressure = compressor pressure + metering device pressure
B. spring pressure = evaporator pressure + bulb pressure
C. evaporator pressure = bulb pressure + spring pressure
D. bulb pressure = evaporator pressure + spring pressure |
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Definition
| D. Bulb pressure = evaporator pressure + spring pressure |
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Term
A cap tube can adjust to wide varying load conditions....
A. true
B. false |
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Definition
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Term
A system with high pressures on both low and high sides with a low superheat and a high sub-cool has?
A. high condenser load
B. overcharged
C. undercharged
D. has a low side refrigerant leak |
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Definition
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Term
A system with low pressures on both low and high sides with a high superheat and a low sub-cool has?
A. high condenser load
B. overcharged
C. undercharged
D. has a low side refrigerant leak |
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Definition
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Term
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Definition
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Term
On an automatic expansion valve to increase evaporator pressure?
A. remove the insulation from the bulb
B. turn the adjustment counterclockwise
C. turn the adjustment clockwise
D. add more refrigerant |
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Definition
| C. turn the adjustment clockwise |
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Term
| Specific heat capacity is? |
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Definition
| Is the amount of heat required to increase a rise in temperature. |
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Term
A centrifugal compressor moves refrigerant by?
A. reciprocation
B. positive displacement
C. centrifugal force
D. Venturi effect |
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Definition
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Term
Reciprocating compressor valves operate by?
A. pressure differences
B. superheat
C. latent heat
D. liquid pressure |
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Definition
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Term
Induced fan's?
A. pull's air across the coil
B. pushes air across the coil
C. water droplets through the coil
D. use's centrifugal force |
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Definition
| A. Pull's air across the coil |
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Term
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Definition
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Term
| Refrigerant enters the the evaporator as a? |
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Definition
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Term
A magnehelic measures?
A. static pressure drop
B. velocity pressure
C. water pressure
D. temperature |
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Definition
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Term
Water into the system can cause?
A. valve failure
B. corrosion of metals
C. freeze up at the metering device
D. all of the above |
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Definition
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Term
If the condenser fan goes out what will happen?
A. system will have higher sub-cooling
B. the TXV will compensate for any problems on the systems high side
C. the compressor will draw lower amps
D. the system pressure will increase |
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Definition
| D. The system pressure will increase |
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Term
A perfect vacuum is?
A. 29.9"HG
B. 0" PSIG
C. 0" HG
D. 500 microns |
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Definition
A. 29.9"HG
C. 0" HG
D. 500 microns |
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Term
A 13 seer 5 ton systems have bigger condenser coil's than a 10 seer 5 ton system....
A. true
B. false |
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Definition
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Term
To find superheat you must?
A. add the suction line temperature too the evaporator saturation temperature
B. subtract evaporator saturation temperature from suction line temperature
C. Subtract the evaporator saturation temperature from the condenser saturation temperature
D. Weigh the refrigerant |
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Definition
| B. Subtract evaporator saturation temperature from suction line temperature |
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Term
To find sub-cooling?
A. subtract condenser saturation temperature from liquid line temperature
B. add condenser saturation to liquid line temp and divide by 2
C. take the indoor wet bulb and the outdoor dry bulb
D. subtract the evaporator saturation temperature from from the liquid line temperature |
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Definition
| A. Subtract condenser saturation temperature from liquid line temperature |
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Term
When evacuating a system you must use?
A. a vacuum pump, manifold gauges, and a micron gauge
B. a vacuum pump, manifold gauges, and a digital psychrometer
C. a recovery tank, manifold gauges, and a weight scale
D. a micron gauge, vacuum, and a weight scale |
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Definition
| A. A vacuum pump, manifold gauges, and a micron gauge |
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Term
How do you check static pressure?
A. with system off reading only the high side gauge pressure
B.with the system running on the high side gauge
C. with the system off on the low side gauge
D. with the system running on the low side gauge |
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Definition
| A. With system off reading only the high side gauge pressure |
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Term
| What 2 temperature readings do you need to use a charging chart for? |
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Definition
| Indoor wet bulb and out door dry bulb |
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Term
latent heat is rated in?
A. sensible heat
B. kelin temperature
C. rankine temperature
D. BTU's |
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Definition
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Term
| The condenser fan blade is a? |
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Definition
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Term
On a TXV to increase superheat the technician must?
A. Fully front seat the adjustment
B. fully back the seat adjustment
C. turn the adjustment counterclockwise
D. turn the adjustment clockwise |
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Definition
| D. Turn the adjustment clockwise |
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Term
Balance port TXV's ?
A. have a wider range of operating conditions
B. are sensitive to system changes
C. are used on only chillers
D. can operate only in cold climates |
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Definition
| A. Have a wider range of operating conditions |
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