Page 1 of 141
Refrigeration Engineer License Exam COMPLETE
QUESTIONS AND DETAILED SOLUTIONS LATEST
UPDATE THIS YEAR-JUST RELEASED
Summarized Exam Coverage – Refrigeration Engineer License
The exam covers refrigeration cycle theory, components (compressors, condensers, evaporators,
metering devices), system operation and troubleshooting, refrigerants (CFCs, HCFCs, HFCs, natural) and
environmental regulations (EPA Section 608, Montreal Protocol), safety (pressure vessels, relief valves,
ammonia safety, confined space, lockout/tagout), electrical controls and motor controllers, heat
transfer principles, defrost methods, psychrometrics, system efficiency (superheat, subcooling,
compression ratio), applicable building and fire codes (varies by jurisdiction), and operator
responsibilities for commercial/industrial systems.
1. A refrigeration compressor is running but not building any discharge pressure. The most likely cause
of this condition is which of the following mechanical failures?
A) Broken connecting rod or valve plate
B) Dirty condenser coil
C) Overcharged refrigerant system
D) Restricted liquid line filter dryer
Answer: A – A broken connecting rod prevents compression, while a dirty condenser or overcharge
would still build pressure (though abnormally high in the latter case).
2. A technician measures the suction pressure at 40 psig and the evaporator outlet temperature at 25°F
while using R-22 refrigerant. What is the approximate superheat of this system?
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A) 25°F
B) 15°F
C) 5°F
D) 50°F
Answer: B – R-22 at 40 psig has a saturation temperature of approximately 10°F; superheat = measured
temperature minus saturation temperature = 25°F – 10°F = 15°F .
3. The sensing bulb for a thermostatic expansion valve (TXV) must be mounted on which line to control
superheat properly?
A) Liquid line before the evaporator
B) Suction line near the evaporator outlet
C) Discharge line leaving the compressor
D) Condenser liquid outlet line
Answer: B – The TXV bulb must be strapped to the suction line to sense evaporator outlet superheat
and adjust refrigerant flow accordingly .
4. An oil safety switch (oil pressure differential switch) is designed to protect a refrigeration compressor
from operating under which dangerous condition?
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A) High discharge pressure
B) Low oil pressure for a prolonged period
C) High suction pressure
D) Overcurrent in the motor windings
Answer: B – The oil safety switch shuts down the compressor if the oil pressure fails to establish or
maintain a minimum net pressure within a given time frame .
5. A walk-in freezer is not pulling down to temperature, and the evaporator coil is completely iced over
from front to back. What is the most likely cause of this thick ice accumulation?
A) Refrigerant undercharge
B) Defective defrost heater or defrost termination switch
C) Oversized TXV feeding the evaporator
D) High ambient temperature in the compressor room
Answer: B – Defrost failure is the primary cause of solid ice buildup, as the coil never sheds accumulated
frost .
6. R-134a is classified under ASHRAE safety group A1. What does the “A1” designation indicate
regarding the refrigerant’s safety and flammability?
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A) A1 means the refrigerant is highly toxic and flammable
B) A1 means the refrigerant is non-toxic and non-flammable
C) A1 means the refrigerant is mildly toxic but non-flammable
D) A1 means the refrigerant is non-toxic but highly flammable
Answer: B – A1 indicates low toxicity (A) with no flame propagation (1). R-134a is an HFC with zero ODP
but moderate GWP.
7. A compressor is equipped with a crankcase heater. What is the primary function of this electrical
heater in a refrigeration system?
A) To warm up the oil during compressor operation
B) To prevent refrigerant migration and liquid slugging during off-cycles
C) To heat the suction gas before entering the cylinders
D) To reduce the viscosity of the oil for easier starting
Answer: B – The crankcase heater keeps the oil warm, driving off dissolved liquid refrigerant that could
otherwise migrate and cause slugging on start-up .
8. In a water-cooled condenser, the temperature difference between the leaving condenser water and
the condensing temperature of the refrigerant is typically called the:
Refrigeration Engineer License Exam COMPLETE
QUESTIONS AND DETAILED SOLUTIONS LATEST
UPDATE THIS YEAR-JUST RELEASED
Summarized Exam Coverage – Refrigeration Engineer License
The exam covers refrigeration cycle theory, components (compressors, condensers, evaporators,
metering devices), system operation and troubleshooting, refrigerants (CFCs, HCFCs, HFCs, natural) and
environmental regulations (EPA Section 608, Montreal Protocol), safety (pressure vessels, relief valves,
ammonia safety, confined space, lockout/tagout), electrical controls and motor controllers, heat
transfer principles, defrost methods, psychrometrics, system efficiency (superheat, subcooling,
compression ratio), applicable building and fire codes (varies by jurisdiction), and operator
responsibilities for commercial/industrial systems.
1. A refrigeration compressor is running but not building any discharge pressure. The most likely cause
of this condition is which of the following mechanical failures?
A) Broken connecting rod or valve plate
B) Dirty condenser coil
C) Overcharged refrigerant system
D) Restricted liquid line filter dryer
Answer: A – A broken connecting rod prevents compression, while a dirty condenser or overcharge
would still build pressure (though abnormally high in the latter case).
2. A technician measures the suction pressure at 40 psig and the evaporator outlet temperature at 25°F
while using R-22 refrigerant. What is the approximate superheat of this system?
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A) 25°F
B) 15°F
C) 5°F
D) 50°F
Answer: B – R-22 at 40 psig has a saturation temperature of approximately 10°F; superheat = measured
temperature minus saturation temperature = 25°F – 10°F = 15°F .
3. The sensing bulb for a thermostatic expansion valve (TXV) must be mounted on which line to control
superheat properly?
A) Liquid line before the evaporator
B) Suction line near the evaporator outlet
C) Discharge line leaving the compressor
D) Condenser liquid outlet line
Answer: B – The TXV bulb must be strapped to the suction line to sense evaporator outlet superheat
and adjust refrigerant flow accordingly .
4. An oil safety switch (oil pressure differential switch) is designed to protect a refrigeration compressor
from operating under which dangerous condition?
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A) High discharge pressure
B) Low oil pressure for a prolonged period
C) High suction pressure
D) Overcurrent in the motor windings
Answer: B – The oil safety switch shuts down the compressor if the oil pressure fails to establish or
maintain a minimum net pressure within a given time frame .
5. A walk-in freezer is not pulling down to temperature, and the evaporator coil is completely iced over
from front to back. What is the most likely cause of this thick ice accumulation?
A) Refrigerant undercharge
B) Defective defrost heater or defrost termination switch
C) Oversized TXV feeding the evaporator
D) High ambient temperature in the compressor room
Answer: B – Defrost failure is the primary cause of solid ice buildup, as the coil never sheds accumulated
frost .
6. R-134a is classified under ASHRAE safety group A1. What does the “A1” designation indicate
regarding the refrigerant’s safety and flammability?
, Page 4 of 141
A) A1 means the refrigerant is highly toxic and flammable
B) A1 means the refrigerant is non-toxic and non-flammable
C) A1 means the refrigerant is mildly toxic but non-flammable
D) A1 means the refrigerant is non-toxic but highly flammable
Answer: B – A1 indicates low toxicity (A) with no flame propagation (1). R-134a is an HFC with zero ODP
but moderate GWP.
7. A compressor is equipped with a crankcase heater. What is the primary function of this electrical
heater in a refrigeration system?
A) To warm up the oil during compressor operation
B) To prevent refrigerant migration and liquid slugging during off-cycles
C) To heat the suction gas before entering the cylinders
D) To reduce the viscosity of the oil for easier starting
Answer: B – The crankcase heater keeps the oil warm, driving off dissolved liquid refrigerant that could
otherwise migrate and cause slugging on start-up .
8. In a water-cooled condenser, the temperature difference between the leaving condenser water and
the condensing temperature of the refrigerant is typically called the:
