Master HVAC Technician Examination
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of refrigerant in an HVAC system?
A) To lubricate the compressor
B) To absorb and release heat during phase changes
C) To increase air pressure in ducts
D) To clean the evaporator coil
Answer: B) To absorb and release heat during phase changes
Rationale: Refrigerant is designed to change states between
liquid and vapor, allowing it to absorb heat indoors during
evaporation and release heat outdoors during condensation.
2. Which component of a refrigeration system raises the pressure of
the refrigerant?
A) Evaporator
B) Expansion valve
, C) Compressor
D) Condenser
Answer: C) Compressor
Rationale: The compressor pressurizes low-pressure vapor
refrigerant, enabling it to flow through the system and release
heat at the condenser.
3. What is superheat?
A) Heat added to liquid refrigerant
B) Temperature below boiling point
C) Heat added to vapor refrigerant above its boiling point
D) Heat removed from air
Answer: C) Heat added to vapor refrigerant above its boiling
point
Rationale: Superheat ensures all liquid refrigerant has
evaporated and the vapor is safely above saturation
temperature before entering the compressor.
4. What is subcooling?
A) Cooling vapor below dew point
B) Cooling liquid refrigerant below its condensation temperature
, C) Heating refrigerant gas
D) Compressing refrigerant
Answer: B) Cooling liquid refrigerant below its condensation
temperature
Rationale: Subcooling ensures liquid refrigerant is fully
condensed and improves system efficiency by preventing flash
gas.
5. Which refrigerant is commonly used in modern residential
systems?
A) R-22
B) R-410A
C) R-12
D) Ammonia
Answer: B) R-410A
Rationale: R-410A is widely used due to higher efficiency and
environmental regulations phasing out R-22.
6. What does the evaporator coil do?
A) Rejects heat outdoors
B) Absorbs heat from indoor air
, C) Compresses refrigerant
D) Filters refrigerant
Answer: B) Absorbs heat from indoor air
Rationale: The evaporator coil allows refrigerant to evaporate
while absorbing heat from the surrounding air.
7. Which law states that pressure increases when volume decreases
(at constant temperature)?
A) Ohm’s Law
B) Boyle’s Law
C) Charles’ Law
D) Dalton’s Law
Answer: B) Boyle’s Law
Rationale: Boyle’s Law describes the inverse relationship
between pressure and volume in gases.
8. What is the function of a thermostatic expansion valve (TXV)?
A) Compress refrigerant
B) Meter refrigerant into evaporator
C) Filter air
D) Increase voltage
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of refrigerant in an HVAC system?
A) To lubricate the compressor
B) To absorb and release heat during phase changes
C) To increase air pressure in ducts
D) To clean the evaporator coil
Answer: B) To absorb and release heat during phase changes
Rationale: Refrigerant is designed to change states between
liquid and vapor, allowing it to absorb heat indoors during
evaporation and release heat outdoors during condensation.
2. Which component of a refrigeration system raises the pressure of
the refrigerant?
A) Evaporator
B) Expansion valve
, C) Compressor
D) Condenser
Answer: C) Compressor
Rationale: The compressor pressurizes low-pressure vapor
refrigerant, enabling it to flow through the system and release
heat at the condenser.
3. What is superheat?
A) Heat added to liquid refrigerant
B) Temperature below boiling point
C) Heat added to vapor refrigerant above its boiling point
D) Heat removed from air
Answer: C) Heat added to vapor refrigerant above its boiling
point
Rationale: Superheat ensures all liquid refrigerant has
evaporated and the vapor is safely above saturation
temperature before entering the compressor.
4. What is subcooling?
A) Cooling vapor below dew point
B) Cooling liquid refrigerant below its condensation temperature
, C) Heating refrigerant gas
D) Compressing refrigerant
Answer: B) Cooling liquid refrigerant below its condensation
temperature
Rationale: Subcooling ensures liquid refrigerant is fully
condensed and improves system efficiency by preventing flash
gas.
5. Which refrigerant is commonly used in modern residential
systems?
A) R-22
B) R-410A
C) R-12
D) Ammonia
Answer: B) R-410A
Rationale: R-410A is widely used due to higher efficiency and
environmental regulations phasing out R-22.
6. What does the evaporator coil do?
A) Rejects heat outdoors
B) Absorbs heat from indoor air
, C) Compresses refrigerant
D) Filters refrigerant
Answer: B) Absorbs heat from indoor air
Rationale: The evaporator coil allows refrigerant to evaporate
while absorbing heat from the surrounding air.
7. Which law states that pressure increases when volume decreases
(at constant temperature)?
A) Ohm’s Law
B) Boyle’s Law
C) Charles’ Law
D) Dalton’s Law
Answer: B) Boyle’s Law
Rationale: Boyle’s Law describes the inverse relationship
between pressure and volume in gases.
8. What is the function of a thermostatic expansion valve (TXV)?
A) Compress refrigerant
B) Meter refrigerant into evaporator
C) Filter air
D) Increase voltage
