HVAC EXCELLENCE TEST PAPER UPDATED EXAM
QUESTIONS AND SOLUTIONS RATED A+
✔✔A decrease in superheat causes the thermostatic expansion valve to - ✔✔Close
✔✔A rise in evaporator pressure causes the automatic expansion valve to begin to -
✔✔close
✔✔a thermal-electric ( solid state) expansion valveis controlled by - ✔✔NTC Thermistor
✔✔In a Direct expansion (DX) evaporator system, the refrigerant enters the evaporator
as - ✔✔a mixture of liquid with some "flash gas"
✔✔In the Evaporator - ✔✔Latent heat is transferred from the refrigerated space to the
refrigerant
✔✔A Liquid line filter drier should be placed between the - ✔✔Condenser and metering
device
✔✔The only way to minimize flash gas is by - ✔✔sub-cooling the liquid refrigerant
entering the metering device closer to the evaporator temperature
✔✔A liquid reciever is used to - ✔✔Store liquid refrigerant
✔✔An accumulator is used to - ✔✔Prevent liquid refrigerant from reaching the
compressor
✔✔A sight glass would normally be located - ✔✔in the liquied line, before the metering
device
✔✔Bubbles in the sight glass could be an indication of - ✔✔Low compressor capacity
✔✔The oil separator is installed in the - ✔✔Discharge line
✔✔Which of the following is true of a solenoid valve in a pump down system? - ✔✔It is
located before the metering device
✔✔the purpose of an evaporator pressure regulating valve (EPT) is to: - ✔✔prevent
evaporator pressure from falling below a set limit
✔✔A liquid-to-suction heat exchanger is often used to - ✔✔Increase liquid subcooling
✔✔The oil pressure safetyswitch is operated by - ✔✔the difference between crankcase
pressure and oil pressure
, ✔✔A low pressure cut-off switch is used to - ✔✔Establish a minimum operating
pressure in the evaporator
✔✔A partially iced over evaporator can be caused by - ✔✔an undercharge
✔✔____ can be used for leak detection with ALL high pressure refrigerants - ✔✔Soap
Bubbles
✔✔The flow rate of a TXV used in R410A systems as compared to R22 system is: -
✔✔Approximately 15% lower
✔✔When using an electronic leak detecter, the sensing probe - ✔✔should be moved at
approximately 1 inch every second
✔✔Moisture in the refrigeration system will cause - ✔✔Compressure Failure
✔✔In order to remove as much moisture as possible from a system - ✔✔Triple
evacuate the system to 500 microns with a deep vacuum pump
✔✔What kind of gauge is used to measure microns? - ✔✔A compound gauge
✔✔Water will vaporize at ____ temperature in a 28 inch mercury vacuum - ✔✔100
degrees faranheit
✔✔After a system has been opened and the compressor changed, the service
technician must: - ✔✔replace the filter drier, leak check, evacuate and charge
✔✔Back seating a two way service valve results in - ✔✔closed service port with normal
system flow
✔✔before a vapor/ compression system is opened for service - ✔✔the refrigerant must
be recovered using approved equipment
✔✔The R 410A compound gauge reads 124 psig and the suction line temp. at the
condensing unit is 54 degrees F. what is the operating system superheat? - ✔✔12
degrees faranheit
✔✔When topping off an operating system containing a blended refrigerant -
✔✔introduce the refrigerant a a liquid into the low side using a throttling valve.
✔✔a partially clogged capillary tube metering device can cause - ✔✔a starved
evaporator
QUESTIONS AND SOLUTIONS RATED A+
✔✔A decrease in superheat causes the thermostatic expansion valve to - ✔✔Close
✔✔A rise in evaporator pressure causes the automatic expansion valve to begin to -
✔✔close
✔✔a thermal-electric ( solid state) expansion valveis controlled by - ✔✔NTC Thermistor
✔✔In a Direct expansion (DX) evaporator system, the refrigerant enters the evaporator
as - ✔✔a mixture of liquid with some "flash gas"
✔✔In the Evaporator - ✔✔Latent heat is transferred from the refrigerated space to the
refrigerant
✔✔A Liquid line filter drier should be placed between the - ✔✔Condenser and metering
device
✔✔The only way to minimize flash gas is by - ✔✔sub-cooling the liquid refrigerant
entering the metering device closer to the evaporator temperature
✔✔A liquid reciever is used to - ✔✔Store liquid refrigerant
✔✔An accumulator is used to - ✔✔Prevent liquid refrigerant from reaching the
compressor
✔✔A sight glass would normally be located - ✔✔in the liquied line, before the metering
device
✔✔Bubbles in the sight glass could be an indication of - ✔✔Low compressor capacity
✔✔The oil separator is installed in the - ✔✔Discharge line
✔✔Which of the following is true of a solenoid valve in a pump down system? - ✔✔It is
located before the metering device
✔✔the purpose of an evaporator pressure regulating valve (EPT) is to: - ✔✔prevent
evaporator pressure from falling below a set limit
✔✔A liquid-to-suction heat exchanger is often used to - ✔✔Increase liquid subcooling
✔✔The oil pressure safetyswitch is operated by - ✔✔the difference between crankcase
pressure and oil pressure
, ✔✔A low pressure cut-off switch is used to - ✔✔Establish a minimum operating
pressure in the evaporator
✔✔A partially iced over evaporator can be caused by - ✔✔an undercharge
✔✔____ can be used for leak detection with ALL high pressure refrigerants - ✔✔Soap
Bubbles
✔✔The flow rate of a TXV used in R410A systems as compared to R22 system is: -
✔✔Approximately 15% lower
✔✔When using an electronic leak detecter, the sensing probe - ✔✔should be moved at
approximately 1 inch every second
✔✔Moisture in the refrigeration system will cause - ✔✔Compressure Failure
✔✔In order to remove as much moisture as possible from a system - ✔✔Triple
evacuate the system to 500 microns with a deep vacuum pump
✔✔What kind of gauge is used to measure microns? - ✔✔A compound gauge
✔✔Water will vaporize at ____ temperature in a 28 inch mercury vacuum - ✔✔100
degrees faranheit
✔✔After a system has been opened and the compressor changed, the service
technician must: - ✔✔replace the filter drier, leak check, evacuate and charge
✔✔Back seating a two way service valve results in - ✔✔closed service port with normal
system flow
✔✔before a vapor/ compression system is opened for service - ✔✔the refrigerant must
be recovered using approved equipment
✔✔The R 410A compound gauge reads 124 psig and the suction line temp. at the
condensing unit is 54 degrees F. what is the operating system superheat? - ✔✔12
degrees faranheit
✔✔When topping off an operating system containing a blended refrigerant -
✔✔introduce the refrigerant a a liquid into the low side using a throttling valve.
✔✔a partially clogged capillary tube metering device can cause - ✔✔a starved
evaporator
