UA STAR HVACR Mastery Certification
Practice Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
Pdf
1. What is the primary function of a thermostatic expansion valve (TXV)?
A. Increase refrigerant pressure
B. Control refrigerant flow into the evaporator
C. Reduce compressor load
D. Store refrigerant
Answer: B
Rationale: The TXV meters refrigerant into the evaporator based on
superheat, ensuring efficient heat absorption.
2. What refrigerant has replaced R-22 in many residential systems?
A. R-11
B. R-134a
C. R-410A
D. R-123
Answer: C
Rationale: R-410A is widely used as a replacement due to its higher
efficiency and zero ozone depletion potential.
,3. What does superheat indicate in a refrigeration system?
A. Liquid refrigerant temperature
B. Vapor refrigerant temperature above saturation
C. Compressor discharge pressure
D. Condenser efficiency
Answer: B
Rationale: Superheat measures how much the vapor temperature exceeds
its boiling point, ensuring no liquid enters the compressor.
4. What component removes moisture from refrigerant?
A. Accumulator
B. Filter drier
C. Receiver
D. Condenser
Answer: B
Rationale: Filter driers contain desiccants that remove moisture and
contaminants from refrigerant.
5. What is the typical airflow required per ton of cooling?
A. 200 CFM
B. 300 CFM
C. 400 CFM
D. 600 CFM
Answer: C
Rationale: Standard HVAC design uses approximately 400 CFM per ton for
proper heat exchange.
6. What law explains the relationship between pressure and temperature of a
gas?
A. Boyle’s Law
B. Charles’s Law
C. Dalton’s Law
D. Ohm’s Law
Answer: B
, Rationale: Charles’s Law states that gas volume is directly proportional to
temperature at constant pressure.
7. What is subcooling?
A. Heating refrigerant above saturation
B. Cooling liquid refrigerant below saturation temperature
C. Removing moisture
D. Increasing pressure
Answer: B
Rationale: Subcooling ensures liquid refrigerant remains in liquid form
before entering the expansion device.
8. Which component increases refrigerant pressure?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
Answer: C
Rationale: The compressor raises refrigerant pressure and temperature to
move it through the system.
9. What is the purpose of a reversing valve?
A. Control airflow
B. Reverse refrigerant flow for heating/cooling
C. Reduce pressure
D. Filter refrigerant
Answer: B
Rationale: Heat pumps use reversing valves to switch between heating
and cooling modes.
10.What type of motor is commonly used in HVAC blowers?
A. DC motor
B. Universal motor
C. Permanent split capacitor motor
D. Stepper motor
Practice Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
1. What is the primary function of a thermostatic expansion valve (TXV)?
A. Increase refrigerant pressure
B. Control refrigerant flow into the evaporator
C. Reduce compressor load
D. Store refrigerant
Answer: B
Rationale: The TXV meters refrigerant into the evaporator based on
superheat, ensuring efficient heat absorption.
2. What refrigerant has replaced R-22 in many residential systems?
A. R-11
B. R-134a
C. R-410A
D. R-123
Answer: C
Rationale: R-410A is widely used as a replacement due to its higher
efficiency and zero ozone depletion potential.
,3. What does superheat indicate in a refrigeration system?
A. Liquid refrigerant temperature
B. Vapor refrigerant temperature above saturation
C. Compressor discharge pressure
D. Condenser efficiency
Answer: B
Rationale: Superheat measures how much the vapor temperature exceeds
its boiling point, ensuring no liquid enters the compressor.
4. What component removes moisture from refrigerant?
A. Accumulator
B. Filter drier
C. Receiver
D. Condenser
Answer: B
Rationale: Filter driers contain desiccants that remove moisture and
contaminants from refrigerant.
5. What is the typical airflow required per ton of cooling?
A. 200 CFM
B. 300 CFM
C. 400 CFM
D. 600 CFM
Answer: C
Rationale: Standard HVAC design uses approximately 400 CFM per ton for
proper heat exchange.
6. What law explains the relationship between pressure and temperature of a
gas?
A. Boyle’s Law
B. Charles’s Law
C. Dalton’s Law
D. Ohm’s Law
Answer: B
, Rationale: Charles’s Law states that gas volume is directly proportional to
temperature at constant pressure.
7. What is subcooling?
A. Heating refrigerant above saturation
B. Cooling liquid refrigerant below saturation temperature
C. Removing moisture
D. Increasing pressure
Answer: B
Rationale: Subcooling ensures liquid refrigerant remains in liquid form
before entering the expansion device.
8. Which component increases refrigerant pressure?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
Answer: C
Rationale: The compressor raises refrigerant pressure and temperature to
move it through the system.
9. What is the purpose of a reversing valve?
A. Control airflow
B. Reverse refrigerant flow for heating/cooling
C. Reduce pressure
D. Filter refrigerant
Answer: B
Rationale: Heat pumps use reversing valves to switch between heating
and cooling modes.
10.What type of motor is commonly used in HVAC blowers?
A. DC motor
B. Universal motor
C. Permanent split capacitor motor
D. Stepper motor
