DC HVAC Journeyman Mechanic Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. Which refrigerant recovery procedure is required before opening a
sealed refrigeration system for repair?
A. Venting the refrigerant outdoors
B. Recovering refrigerant into an approved recovery cylinder
C. Mixing refrigerants in one container
D. Increasing system pressure to release refrigerant
Answer: B. Recovering refrigerant into an approved recovery cylinder
Rationale: Refrigerant must be recovered into an approved cylinder to
prevent environmental release and comply with EPA regulations governing
refrigerant handling.
2. What is the primary function of a compressor in an HVAC refrigeration
cycle?
A. Absorb heat from indoor air
B. Convert liquid refrigerant into vapor
C. Increase refrigerant pressure and circulate refrigerant
D. Remove moisture from refrigerant
Answer: C. Increase refrigerant pressure and circulate refrigerant
,Rationale: The compressor raises the pressure and temperature of
refrigerant vapor and moves it through the refrigeration system.
3. In a typical vapor-compression refrigeration system, where does
refrigerant absorb heat?
A. Condenser coil
B. Evaporator coil
C. Compressor shell
D. Receiver tank
Answer: B. Evaporator coil
Rationale: The evaporator absorbs heat from the conditioned space as
refrigerant changes from liquid to vapor.
4. What instrument is used to measure refrigerant pressure in an HVAC
system?
A. Clamp meter
B. Manifold gauge set
C. Megohmmeter
D. Psychrometer
Answer: B. Manifold gauge set
Rationale: A manifold gauge set measures suction and discharge pressures
to help diagnose refrigeration system operation.
5. What is the purpose of superheat measurement?
A. Determine compressor voltage
B. Measure refrigerant temperature above saturation temperature
C. Measure airflow volume
D. Check electrical resistance
Answer: B. Measure refrigerant temperature above saturation temperature
,Rationale: Superheat confirms that refrigerant entering the compressor is
fully vaporized and helps evaluate system charge and operation.
6. What condition commonly results from an undercharged refrigeration
system?
A. High suction pressure
B. Low superheat
C. Low suction pressure and high superheat
D. Flooded compressor
Answer: C. Low suction pressure and high superheat
Rationale: An undercharged system has insufficient refrigerant flow,
causing the evaporator to starve and increasing superheat.
7. Which component removes heat from refrigerant vapor and
condenses it into liquid?
A. Expansion valve
B. Evaporator
C. Condenser
D. Accumulator
Answer: C. Condenser
Rationale: The condenser rejects heat to the surrounding air or water and
changes refrigerant vapor into liquid.
8. What is the purpose of an expansion valve in an HVAC system?
A. Increase refrigerant pressure
B. Meter refrigerant flow into the evaporator
C. Remove oil from refrigerant
D. Cool compressor windings
Answer: B. Meter refrigerant flow into the evaporator
, Rationale: The expansion valve controls the amount of refrigerant entering
the evaporator while reducing pressure.
9. Which type of motor is commonly used for modern variable-speed
HVAC blower applications?
A. Universal motor
B. ECM motor
C. Shaded-pole motor
D. Series-wound motor
Answer: B. ECM motor
Rationale: Electronically commutated motors provide improved efficiency
and variable-speed control in HVAC equipment.
10. What is the purpose of a thermostat in an HVAC system?
A. Increase refrigerant pressure
B. Control indoor temperature by operating equipment
C. Filter refrigerant
D. Measure humidity only
Answer: B. Control indoor temperature by operating equipment
Rationale: A thermostat senses temperature conditions and signals heating
or cooling equipment to operate.
11. Which tool is used to measure dry-bulb and wet-bulb
temperatures?
A. Psychrometer
B. Micrometer
C. Ohmmeter
D. Tachometer
Answer: A. Psychrometer
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. Which refrigerant recovery procedure is required before opening a
sealed refrigeration system for repair?
A. Venting the refrigerant outdoors
B. Recovering refrigerant into an approved recovery cylinder
C. Mixing refrigerants in one container
D. Increasing system pressure to release refrigerant
Answer: B. Recovering refrigerant into an approved recovery cylinder
Rationale: Refrigerant must be recovered into an approved cylinder to
prevent environmental release and comply with EPA regulations governing
refrigerant handling.
2. What is the primary function of a compressor in an HVAC refrigeration
cycle?
A. Absorb heat from indoor air
B. Convert liquid refrigerant into vapor
C. Increase refrigerant pressure and circulate refrigerant
D. Remove moisture from refrigerant
Answer: C. Increase refrigerant pressure and circulate refrigerant
,Rationale: The compressor raises the pressure and temperature of
refrigerant vapor and moves it through the refrigeration system.
3. In a typical vapor-compression refrigeration system, where does
refrigerant absorb heat?
A. Condenser coil
B. Evaporator coil
C. Compressor shell
D. Receiver tank
Answer: B. Evaporator coil
Rationale: The evaporator absorbs heat from the conditioned space as
refrigerant changes from liquid to vapor.
4. What instrument is used to measure refrigerant pressure in an HVAC
system?
A. Clamp meter
B. Manifold gauge set
C. Megohmmeter
D. Psychrometer
Answer: B. Manifold gauge set
Rationale: A manifold gauge set measures suction and discharge pressures
to help diagnose refrigeration system operation.
5. What is the purpose of superheat measurement?
A. Determine compressor voltage
B. Measure refrigerant temperature above saturation temperature
C. Measure airflow volume
D. Check electrical resistance
Answer: B. Measure refrigerant temperature above saturation temperature
,Rationale: Superheat confirms that refrigerant entering the compressor is
fully vaporized and helps evaluate system charge and operation.
6. What condition commonly results from an undercharged refrigeration
system?
A. High suction pressure
B. Low superheat
C. Low suction pressure and high superheat
D. Flooded compressor
Answer: C. Low suction pressure and high superheat
Rationale: An undercharged system has insufficient refrigerant flow,
causing the evaporator to starve and increasing superheat.
7. Which component removes heat from refrigerant vapor and
condenses it into liquid?
A. Expansion valve
B. Evaporator
C. Condenser
D. Accumulator
Answer: C. Condenser
Rationale: The condenser rejects heat to the surrounding air or water and
changes refrigerant vapor into liquid.
8. What is the purpose of an expansion valve in an HVAC system?
A. Increase refrigerant pressure
B. Meter refrigerant flow into the evaporator
C. Remove oil from refrigerant
D. Cool compressor windings
Answer: B. Meter refrigerant flow into the evaporator
, Rationale: The expansion valve controls the amount of refrigerant entering
the evaporator while reducing pressure.
9. Which type of motor is commonly used for modern variable-speed
HVAC blower applications?
A. Universal motor
B. ECM motor
C. Shaded-pole motor
D. Series-wound motor
Answer: B. ECM motor
Rationale: Electronically commutated motors provide improved efficiency
and variable-speed control in HVAC equipment.
10. What is the purpose of a thermostat in an HVAC system?
A. Increase refrigerant pressure
B. Control indoor temperature by operating equipment
C. Filter refrigerant
D. Measure humidity only
Answer: B. Control indoor temperature by operating equipment
Rationale: A thermostat senses temperature conditions and signals heating
or cooling equipment to operate.
11. Which tool is used to measure dry-bulb and wet-bulb
temperatures?
A. Psychrometer
B. Micrometer
C. Ohmmeter
D. Tachometer
Answer: A. Psychrometer
