MM ADVANCEMENT STUDY GUIDE EXAM QUESTIONS
WITH RIGHT ACCURATE ANSWERS 2026 – 2027 .
How are refrigerant leaks detected? - Correct Answer -By use of an electronic tester or by the
soapsuds test method
Which Naval Ship Technical Manual (NSTM) chapter will give you specific information on
the operation and maintenance of refrigeration systems - Correct Answer -516
Which type of lube oil system is found on high speed refrigerant compressors - Correct
Answer -Force-feed lubricating
Which speed does high speed centrifugal refrigerant compressors operate at? - Correct
Answer -1,500 RPM's
Which type of material is refrigerant piping made out of? - Correct Answer -ACR seamless
copper piping
Refrigerant Thermostatic Expansion Valves (TXV) are set to maintain a superheat range of
how many degrees at the cooling-coil outlet? - Correct Answer -4-12°F
Which term is defined as the appearance of frost on the suction line extending as far back as
the compressor? - Correct Answer -Frosting Back
Which system discharge pressure is the refrigerant water regulating valve set to maintain? -
Correct Answer -125 psig
What is the first indication of a refrigerant shaft seal failure? - Correct Answer -Oil leakage
What should never be done when installing a new refrigerant shaft seal? - Correct Answer -
Handling seals with your fingers, surgical gloves should be used for seal installation
1
,Which Naval Ship Technical Manual (NSTM) chapter should be read before handling
refrigerant bottles? - Correct Answer -670
Which manner must refrigerant bottles always be stored in? - Correct Answer -In a cool, dry
place, in an upright position firmly anchored
What is the maximum temperature that refrigerant bottles should be exposed to? - Correct
Answer -130°F
Why are refrigerants considered to be deadly? - Correct Answer -Halocarbons
Which measurement is the capacity of a refrigeration plant always expressed in? - Correct
Answer -Tons of refrigerant
The refrigerant liquid strainer is designed to protect what? - Correct Answer -The solenoid
valves and TXV
Which type of switch automatically stops a refrigerant compressor when a failure of
circulating water supply occurs? - Correct Answer -Water failure
Which type of refrigerant is replacing R-11 and R-12 systems? - Correct Answer -R-134
What is the allowable monthly leakage rate of the total refrigerant charge minus the reported
accidental or unintentional releases? - Correct Answer -35%
How often is testing of refrigerant systems for leaks accomplished IAW PMS? - Correct
Answer -Semi-annually
What is not permitted in the vicinity of performing recovery of refrigerant? - Correct Answer
-Hot work
Refrigerant usage logs must be kept when the refrigeration plant holds how many or more
pounds of refrigerant? - Correct Answer -50
2
,How often at a minimum must refrigerant usage logs be reviewed? - Correct Answer -
Monthly
What controls the capacity of a refrigerant compressor? - Correct Answer -Cylinder
unloading and loading
Where is the compressor capacity control valve located? - Correct Answer -Compressor
crankcase cover
What actuates the compressor capacity control valve? - Correct Answer -Oil pressure
Which pressure is the compressor pumped down to when testing the compressor discharge
valves for proper operation? - Correct Answer -2 psig
What is the problem if while conducting a compressor discharge valve test, the discharge
pressure drops at a rate in excess of 3 pounds a minute and the crankcase pressure rises? -
Correct Answer -Compressor discharge valve leakage
Compressor suction valves are working satisfactorily when checking them for proper
operation if the compressor can hold a minimum of how many inches of vacuum with the line
stop valve shut? - Correct Answer -20
Which Naval Ship Technical Manual (NSTM) chapter contains information on re- tubing
refrigerant condensers? - Correct Answer -516
Under normal conditions, what percentage of the full refrigerant load should the refrigerant
charge be with the compressor stopped under normal conditions? - Correct Answer -85%
Which system action must be taken if the refrigerant compressor indicates a temperature of
the liquid leaving the receiver is more than 5°F lower than the temperature corresponding to
the discharge pressure? - Correct Answer -Purging
Which temperature should the air be heated to when using a dehydrator to remove moisture
during system evacuation? - Correct Answer -240°F
3
, What is used to remove the remaining moisture from the refrigeration system after
completing the dehydrator stage of moisture evacuation? - Correct Answer -Vacuum pump
Which temperature is the dehydration process considered complete? - Correct Answer -35°F
Which temperature is the dehydrator drying agent heated to for 12 hours when it is being
reactivated? - Correct Answer -300°F
Which type of air conditioning control system would you expect to find on a system that uses
re-heaters employing a thermostatic element actuating two interlocked switches? - Correct
Answer -Two-position dual control (2PD)
Which type of devices are used to check thermostats and humidistats for proper operation
along with a reliable humidity indicator? - Correct Answer -Calibrated thermometers
How often at a minimum is it recommended to test the air conditioning control system for
proper operation? - Correct Answer -Quarterly
What should be adjusted along with examining the fastening of the thermal bulb if your air
conditioning plant is operating with a low condensing pressure causing liquid refrigerant to
flood back from the evaporator? - Correct Answer -Expansion Valve
Which action should be taken if your air conditioning plant is operating with a high
condensing pressures causing too much liquid in the receiver submerging the condenser tubes
in liquid refrigerant? - Correct Answer -Draw off liquid into service cylinder
What should be adjusted or replaced if your air conditioning compressor suddenly loses oil
from the crankcase and liquid refrigerant is slugging back to the compressor crankcase? -
Correct Answer -Expansion valve
Inspecting solenoid coils, cleaning valves, or which other action must be taken if you suspect
the thermostatic cooling-coil magnetic valve is not opening? - Correct Answer -Adjust pilots
ow many personnel must be present when charging a refrigeration system? - Correct Answer
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4
WITH RIGHT ACCURATE ANSWERS 2026 – 2027 .
How are refrigerant leaks detected? - Correct Answer -By use of an electronic tester or by the
soapsuds test method
Which Naval Ship Technical Manual (NSTM) chapter will give you specific information on
the operation and maintenance of refrigeration systems - Correct Answer -516
Which type of lube oil system is found on high speed refrigerant compressors - Correct
Answer -Force-feed lubricating
Which speed does high speed centrifugal refrigerant compressors operate at? - Correct
Answer -1,500 RPM's
Which type of material is refrigerant piping made out of? - Correct Answer -ACR seamless
copper piping
Refrigerant Thermostatic Expansion Valves (TXV) are set to maintain a superheat range of
how many degrees at the cooling-coil outlet? - Correct Answer -4-12°F
Which term is defined as the appearance of frost on the suction line extending as far back as
the compressor? - Correct Answer -Frosting Back
Which system discharge pressure is the refrigerant water regulating valve set to maintain? -
Correct Answer -125 psig
What is the first indication of a refrigerant shaft seal failure? - Correct Answer -Oil leakage
What should never be done when installing a new refrigerant shaft seal? - Correct Answer -
Handling seals with your fingers, surgical gloves should be used for seal installation
1
,Which Naval Ship Technical Manual (NSTM) chapter should be read before handling
refrigerant bottles? - Correct Answer -670
Which manner must refrigerant bottles always be stored in? - Correct Answer -In a cool, dry
place, in an upright position firmly anchored
What is the maximum temperature that refrigerant bottles should be exposed to? - Correct
Answer -130°F
Why are refrigerants considered to be deadly? - Correct Answer -Halocarbons
Which measurement is the capacity of a refrigeration plant always expressed in? - Correct
Answer -Tons of refrigerant
The refrigerant liquid strainer is designed to protect what? - Correct Answer -The solenoid
valves and TXV
Which type of switch automatically stops a refrigerant compressor when a failure of
circulating water supply occurs? - Correct Answer -Water failure
Which type of refrigerant is replacing R-11 and R-12 systems? - Correct Answer -R-134
What is the allowable monthly leakage rate of the total refrigerant charge minus the reported
accidental or unintentional releases? - Correct Answer -35%
How often is testing of refrigerant systems for leaks accomplished IAW PMS? - Correct
Answer -Semi-annually
What is not permitted in the vicinity of performing recovery of refrigerant? - Correct Answer
-Hot work
Refrigerant usage logs must be kept when the refrigeration plant holds how many or more
pounds of refrigerant? - Correct Answer -50
2
,How often at a minimum must refrigerant usage logs be reviewed? - Correct Answer -
Monthly
What controls the capacity of a refrigerant compressor? - Correct Answer -Cylinder
unloading and loading
Where is the compressor capacity control valve located? - Correct Answer -Compressor
crankcase cover
What actuates the compressor capacity control valve? - Correct Answer -Oil pressure
Which pressure is the compressor pumped down to when testing the compressor discharge
valves for proper operation? - Correct Answer -2 psig
What is the problem if while conducting a compressor discharge valve test, the discharge
pressure drops at a rate in excess of 3 pounds a minute and the crankcase pressure rises? -
Correct Answer -Compressor discharge valve leakage
Compressor suction valves are working satisfactorily when checking them for proper
operation if the compressor can hold a minimum of how many inches of vacuum with the line
stop valve shut? - Correct Answer -20
Which Naval Ship Technical Manual (NSTM) chapter contains information on re- tubing
refrigerant condensers? - Correct Answer -516
Under normal conditions, what percentage of the full refrigerant load should the refrigerant
charge be with the compressor stopped under normal conditions? - Correct Answer -85%
Which system action must be taken if the refrigerant compressor indicates a temperature of
the liquid leaving the receiver is more than 5°F lower than the temperature corresponding to
the discharge pressure? - Correct Answer -Purging
Which temperature should the air be heated to when using a dehydrator to remove moisture
during system evacuation? - Correct Answer -240°F
3
, What is used to remove the remaining moisture from the refrigeration system after
completing the dehydrator stage of moisture evacuation? - Correct Answer -Vacuum pump
Which temperature is the dehydration process considered complete? - Correct Answer -35°F
Which temperature is the dehydrator drying agent heated to for 12 hours when it is being
reactivated? - Correct Answer -300°F
Which type of air conditioning control system would you expect to find on a system that uses
re-heaters employing a thermostatic element actuating two interlocked switches? - Correct
Answer -Two-position dual control (2PD)
Which type of devices are used to check thermostats and humidistats for proper operation
along with a reliable humidity indicator? - Correct Answer -Calibrated thermometers
How often at a minimum is it recommended to test the air conditioning control system for
proper operation? - Correct Answer -Quarterly
What should be adjusted along with examining the fastening of the thermal bulb if your air
conditioning plant is operating with a low condensing pressure causing liquid refrigerant to
flood back from the evaporator? - Correct Answer -Expansion Valve
Which action should be taken if your air conditioning plant is operating with a high
condensing pressures causing too much liquid in the receiver submerging the condenser tubes
in liquid refrigerant? - Correct Answer -Draw off liquid into service cylinder
What should be adjusted or replaced if your air conditioning compressor suddenly loses oil
from the crankcase and liquid refrigerant is slugging back to the compressor crankcase? -
Correct Answer -Expansion valve
Inspecting solenoid coils, cleaning valves, or which other action must be taken if you suspect
the thermostatic cooling-coil magnetic valve is not opening? - Correct Answer -Adjust pilots
ow many personnel must be present when charging a refrigeration system? - Correct Answer
-248
4
