NATE Air Conditioning Specialty Certification Exam
2026/2027 – Questions and Answers with Rationales
TABLE OF CONTENTS
Section 1 — Safety, Codes & Service Practices
Section 2 — HVAC Tools, Measurements & Instruments
Section 3 — Electrical Fundamentals & Controls
Section 4 — Refrigeration Cycle & Refrigerant Theory
Section 5 — Compressors & Compressor Diagnostics
Section 6 — Condensers & Condenser Performance
Section 7 — Evaporators, Airflow & Indoor Coil Performance
Section 8 — Metering Devices, Superheat & Subcooling
Section 9 — Installation, Charging & Commissioning
Section 10 — Troubleshooting, Maintenance & System Performance
SECTION 1 — SAFETY, CODES & SERVICE PRACTICES
Question 1
Before servicing an air-conditioning condensing unit, what should the technician
do first?
A. Add refrigerant
B. Disconnect and verify electrical power is off
C. Remove the compressor
D. Open the service valves
Answer: B
Rationale: Electrical power must be safely disconnected and verified before
servicing energized components.
,Question 2
Which PPE provides protection from refrigerant contacting the eyes?
A. Hearing protection
B. Safety glasses or goggles
C. Dust mask only
D. Cotton cap
Answer: B
Rationale: Liquid refrigerant can cause severe eye injury and frostbite because
of rapid evaporation.
Question 3
Why should liquid refrigerant never be intentionally sprayed onto skin?
A. It causes electrical shock
B. It can cause frostbite
C. It increases humidity
D. It causes high blood pressure
Answer: B
Rationale: Refrigerant rapidly evaporates and removes heat from tissue,
potentially causing frostbite.
Question 4
What gas is commonly used for pressure testing an air-conditioning
refrigeration circuit?
A. Oxygen
B. Nitrogen
C. Hydrogen
D. Propane
Answer: B
,Rationale: Dry nitrogen is inert and suitable for pressure testing when used
within manufacturer and applicable safety limits.
Question 5
Why should oxygen not be used to pressure-test a refrigeration system?
A. It is too expensive
B. It can create a severe combustion or explosion hazard
C. It lowers pressure
D. It damages copper immediately
Answer: B
Rationale: Oxygen under pressure can react dangerously with oil and
combustible materials.
Question 6
What is the purpose of lockout/tagout?
A. Increase cooling capacity
B. Prevent unexpected energization
C. Increase refrigerant pressure
D. Improve airflow
Answer: B
Rationale: Lockout/tagout protects workers from unexpected startup or
energization during service.
Question 7
What should be done with a damaged electrical cord?
A. Continue using it
B. Tape only the exposed conductor
C. Remove it from service
D. Increase the circuit breaker rating
, Answer: C
Rationale: Damaged cords can create shock, short-circuit, and fire hazards.
Question 8
What is the main hazard of an overfilled refrigerant recovery cylinder?
A. Low airflow
B. Excessive pressure from liquid expansion
C. Low humidity
D. Compressor starvation
Answer: B
Rationale: Liquid refrigerant expands as temperature rises. An overfilled
cylinder can develop dangerously high pressure.
Question 9
Why should recovery cylinders be inspected before use?
A. To determine room temperature
B. To verify they are suitable and undamaged
C. To determine airflow
D. To calculate superheat
Answer: B
Rationale: Damaged or unsuitable cylinders may create serious safety hazards.
Question 10
What should a technician do if refrigerant concentration is suspected to be high
in a poorly ventilated room?
A. Continue working
B. Improve ventilation and follow safety procedures
2026/2027 – Questions and Answers with Rationales
TABLE OF CONTENTS
Section 1 — Safety, Codes & Service Practices
Section 2 — HVAC Tools, Measurements & Instruments
Section 3 — Electrical Fundamentals & Controls
Section 4 — Refrigeration Cycle & Refrigerant Theory
Section 5 — Compressors & Compressor Diagnostics
Section 6 — Condensers & Condenser Performance
Section 7 — Evaporators, Airflow & Indoor Coil Performance
Section 8 — Metering Devices, Superheat & Subcooling
Section 9 — Installation, Charging & Commissioning
Section 10 — Troubleshooting, Maintenance & System Performance
SECTION 1 — SAFETY, CODES & SERVICE PRACTICES
Question 1
Before servicing an air-conditioning condensing unit, what should the technician
do first?
A. Add refrigerant
B. Disconnect and verify electrical power is off
C. Remove the compressor
D. Open the service valves
Answer: B
Rationale: Electrical power must be safely disconnected and verified before
servicing energized components.
,Question 2
Which PPE provides protection from refrigerant contacting the eyes?
A. Hearing protection
B. Safety glasses or goggles
C. Dust mask only
D. Cotton cap
Answer: B
Rationale: Liquid refrigerant can cause severe eye injury and frostbite because
of rapid evaporation.
Question 3
Why should liquid refrigerant never be intentionally sprayed onto skin?
A. It causes electrical shock
B. It can cause frostbite
C. It increases humidity
D. It causes high blood pressure
Answer: B
Rationale: Refrigerant rapidly evaporates and removes heat from tissue,
potentially causing frostbite.
Question 4
What gas is commonly used for pressure testing an air-conditioning
refrigeration circuit?
A. Oxygen
B. Nitrogen
C. Hydrogen
D. Propane
Answer: B
,Rationale: Dry nitrogen is inert and suitable for pressure testing when used
within manufacturer and applicable safety limits.
Question 5
Why should oxygen not be used to pressure-test a refrigeration system?
A. It is too expensive
B. It can create a severe combustion or explosion hazard
C. It lowers pressure
D. It damages copper immediately
Answer: B
Rationale: Oxygen under pressure can react dangerously with oil and
combustible materials.
Question 6
What is the purpose of lockout/tagout?
A. Increase cooling capacity
B. Prevent unexpected energization
C. Increase refrigerant pressure
D. Improve airflow
Answer: B
Rationale: Lockout/tagout protects workers from unexpected startup or
energization during service.
Question 7
What should be done with a damaged electrical cord?
A. Continue using it
B. Tape only the exposed conductor
C. Remove it from service
D. Increase the circuit breaker rating
, Answer: C
Rationale: Damaged cords can create shock, short-circuit, and fire hazards.
Question 8
What is the main hazard of an overfilled refrigerant recovery cylinder?
A. Low airflow
B. Excessive pressure from liquid expansion
C. Low humidity
D. Compressor starvation
Answer: B
Rationale: Liquid refrigerant expands as temperature rises. An overfilled
cylinder can develop dangerously high pressure.
Question 9
Why should recovery cylinders be inspected before use?
A. To determine room temperature
B. To verify they are suitable and undamaged
C. To determine airflow
D. To calculate superheat
Answer: B
Rationale: Damaged or unsuitable cylinders may create serious safety hazards.
Question 10
What should a technician do if refrigerant concentration is suspected to be high
in a poorly ventilated room?
A. Continue working
B. Improve ventilation and follow safety procedures
