NATE AIR CONDITIONING SPECIALTY
CERTIFICATION EXAM QUESTION AND
CORRECT ANSWERS(VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. Which component meters refrigerant into the evaporator in a TXV system?
A. Accumulator
B. Receiver-drier
C. Thermostatic expansion valve
D. Compressor
Answer: C. Thermostatic expansion valve
Rationale: The TXV regulates refrigerant flow based on superheat at the
evaporator outlet.
2. What is the primary function of superheat?
A. Increase system capacity
B. Prevent liquid floodback
C. Reduce head pressure
D. Improve airflow
Answer: B. Prevent liquid floodback
Rationale: Superheat ensures only vapor enters the compressor,
protecting it from damage.
3. Which refrigerant is most commonly used in modern residential AC
systems?
A. R-22
B. R-12
C. R-410A
D. R-134a
, Answer: C. R-410A
Rationale: R-410A replaced R-22 due to higher efficiency and no ozone
depletion.
4. High condenser head pressure is most likely caused by:
A. Low airflow over evaporator
B. Undercharge
C. Dirty condenser coil
D. Faulty thermostat
Answer: C. Dirty condenser coil
Rationale: Restricted heat rejection raises condensing pressure.
5. What motor type is commonly used in condenser fan motors?
A. DC motor
B. Stepper motor
C. PSC motor
D. Series motor
Answer: C. PSC motor
Rationale: Permanent split capacitor motors are reliable and efficient for
fan applications.
6. What is the purpose of a liquid line filter-drier?
A. Store refrigerant
B. Increase pressure
C. Remove moisture and contaminants
D. Meter refrigerant
Answer: C. Remove moisture and contaminants
Rationale: Moisture can cause acid formation and component damage.
7. Low suction pressure with normal head pressure usually indicates:
A. Overcharge
B. Restricted metering device
C. Dirty condenser
D. Non-condensables
Answer: B. Restricted metering device
Rationale: Restriction limits refrigerant flow to the evaporator.
, 8. What instrument measures temperature difference across a coil?
A. Manifold gauge
B. Hygrometer
C. Thermometer
D. Micron gauge
Answer: C. Thermometer
Rationale: Temperature change determines sensible heat transfer.
9. The evaporator’s main function is to:
A. Reject heat
B. Compress vapor
C. Absorb heat from indoor air
D. Store refrigerant
Answer: C. Absorb heat from indoor air
Rationale: Heat absorption causes refrigerant to boil into vapor.
10.Which safety control opens the circuit on excessive head pressure?
A. Low-pressure switch
B. Time delay relay
C. High-pressure switch
D. Contactor
Answer: C. High-pressure switch
Rationale: It protects the compressor from dangerous pressures.
11.What causes evaporator icing?
A. High airflow
B. High superheat
C. Low airflow
D. Overheating
Answer: C. Low airflow
Rationale: Insufficient airflow allows coil temperature to drop below
freezing.
12.What is subcooling?
A. Heat added to vapor
B. Cooling liquid refrigerant below saturation temperature
CERTIFICATION EXAM QUESTION AND
CORRECT ANSWERS(VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. Which component meters refrigerant into the evaporator in a TXV system?
A. Accumulator
B. Receiver-drier
C. Thermostatic expansion valve
D. Compressor
Answer: C. Thermostatic expansion valve
Rationale: The TXV regulates refrigerant flow based on superheat at the
evaporator outlet.
2. What is the primary function of superheat?
A. Increase system capacity
B. Prevent liquid floodback
C. Reduce head pressure
D. Improve airflow
Answer: B. Prevent liquid floodback
Rationale: Superheat ensures only vapor enters the compressor,
protecting it from damage.
3. Which refrigerant is most commonly used in modern residential AC
systems?
A. R-22
B. R-12
C. R-410A
D. R-134a
, Answer: C. R-410A
Rationale: R-410A replaced R-22 due to higher efficiency and no ozone
depletion.
4. High condenser head pressure is most likely caused by:
A. Low airflow over evaporator
B. Undercharge
C. Dirty condenser coil
D. Faulty thermostat
Answer: C. Dirty condenser coil
Rationale: Restricted heat rejection raises condensing pressure.
5. What motor type is commonly used in condenser fan motors?
A. DC motor
B. Stepper motor
C. PSC motor
D. Series motor
Answer: C. PSC motor
Rationale: Permanent split capacitor motors are reliable and efficient for
fan applications.
6. What is the purpose of a liquid line filter-drier?
A. Store refrigerant
B. Increase pressure
C. Remove moisture and contaminants
D. Meter refrigerant
Answer: C. Remove moisture and contaminants
Rationale: Moisture can cause acid formation and component damage.
7. Low suction pressure with normal head pressure usually indicates:
A. Overcharge
B. Restricted metering device
C. Dirty condenser
D. Non-condensables
Answer: B. Restricted metering device
Rationale: Restriction limits refrigerant flow to the evaporator.
, 8. What instrument measures temperature difference across a coil?
A. Manifold gauge
B. Hygrometer
C. Thermometer
D. Micron gauge
Answer: C. Thermometer
Rationale: Temperature change determines sensible heat transfer.
9. The evaporator’s main function is to:
A. Reject heat
B. Compress vapor
C. Absorb heat from indoor air
D. Store refrigerant
Answer: C. Absorb heat from indoor air
Rationale: Heat absorption causes refrigerant to boil into vapor.
10.Which safety control opens the circuit on excessive head pressure?
A. Low-pressure switch
B. Time delay relay
C. High-pressure switch
D. Contactor
Answer: C. High-pressure switch
Rationale: It protects the compressor from dangerous pressures.
11.What causes evaporator icing?
A. High airflow
B. High superheat
C. Low airflow
D. Overheating
Answer: C. Low airflow
Rationale: Insufficient airflow allows coil temperature to drop below
freezing.
12.What is subcooling?
A. Heat added to vapor
B. Cooling liquid refrigerant below saturation temperature
