NATE HVAC TECHNICIAN CERTIFICATION EXAMINATION
COMPLETE QUESTIONS AND DETAILED SOLUTIONS
LATEST UPDATE THIS YEAR JUST RELEASED
1. A technician arrives at a residential air-conditioning system that has
stopped operating completely, and the thermostat display is blank.
What should the technician check first?
A. Refrigerant superheat
B. Compressor winding resistance
C. Thermostat power and low-voltage supply
D. Condenser coil cleanliness
Answer: C
Rationale: A blank thermostat can indicate loss of control power, so
verifying the low-voltage circuit and power supply is an appropriate
initial diagnostic step.
2. During an air-conditioning service call, a technician measures
unusually high condensing pressure while indoor airflow is confirmed to
be normal. Which condition should receive immediate attention?
A. Dirty condenser coil
B. Low indoor humidity
C. Oversized evaporator coil
D. Low outdoor temperature
Answer: A
,Rationale: A restricted or dirty condenser coil reduces heat rejection
and can cause elevated condensing temperature and refrigerant
pressure.
3. A technician measures 240 volts across the two supply conductors
feeding a single-phase compressor, but the compressor will not start.
What should be checked next?
A. Outdoor humidity
B. Compressor capacitor and electrical components
C. Evaporator drain slope
D. Refrigerant cylinder temperature
Answer: B
Rationale: Correct supply voltage does not prove that starting
components are functioning; the capacitor, contactor, and compressor
circuit require further testing.
4. A homeowner reports that several rooms remain uncomfortable
even though the central air conditioner runs continuously during hot
weather. Which measurement is most useful initially?
A. Refrigerant cylinder weight
B. Supply and return air temperatures
C. Compressor oil color
D. Outdoor thermostat setting
Answer: B
,Rationale: Comparing return and supply temperatures helps determine
whether the system is producing appropriate cooling before
investigating distribution or capacity issues.
5. Before opening a refrigeration circuit for component replacement,
which procedure is essential for protecting both the technician and the
environment?
A. Vent refrigerant outdoors
B. Recover refrigerant using approved equipment
C. Increase system pressure
D. Remove the compressor oil
Answer: B
Rationale: Refrigerant must be properly recovered with approved
equipment rather than intentionally released, consistent with safe
refrigerant-handling practices.
6. A furnace technician discovers that a gas furnace produces ignition
but the burners shut down shortly afterward. Which component
commonly confirms flame presence?
A. Evaporator thermistor
B. Flame sensor
C. Liquid-line filter
D. Condenser fan blade
Answer: B
Rationale: The flame sensor verifies burner flame to the control
system; a dirty or defective sensor can cause the burners to shut down.
, 7. When measuring electrical resistance across a compressor winding,
why must electrical power be disconnected before using an ohmmeter?
A. Resistance cannot be measured indoors
B. Voltage can damage the meter and create a shock hazard
C. Refrigerant pressure will increase
D. The compressor must remain energized
Answer: B
Rationale: Ohmmeters supply their own testing voltage and should
never be connected to an energized circuit because equipment and
personnel can be endangered.
8. A properly charged cooling system has significantly reduced airflow
across the evaporator because the blower filter is heavily restricted.
What condition could eventually develop?
A. Excessive evaporator temperature
B. Evaporator coil icing
C. Increased condenser airflow
D. Reduced compressor current from improved cooling
Answer: B
Rationale: Restricted airflow can lower evaporator temperature
sufficiently for moisture to freeze on the coil, reducing airflow even
further.
COMPLETE QUESTIONS AND DETAILED SOLUTIONS
LATEST UPDATE THIS YEAR JUST RELEASED
1. A technician arrives at a residential air-conditioning system that has
stopped operating completely, and the thermostat display is blank.
What should the technician check first?
A. Refrigerant superheat
B. Compressor winding resistance
C. Thermostat power and low-voltage supply
D. Condenser coil cleanliness
Answer: C
Rationale: A blank thermostat can indicate loss of control power, so
verifying the low-voltage circuit and power supply is an appropriate
initial diagnostic step.
2. During an air-conditioning service call, a technician measures
unusually high condensing pressure while indoor airflow is confirmed to
be normal. Which condition should receive immediate attention?
A. Dirty condenser coil
B. Low indoor humidity
C. Oversized evaporator coil
D. Low outdoor temperature
Answer: A
,Rationale: A restricted or dirty condenser coil reduces heat rejection
and can cause elevated condensing temperature and refrigerant
pressure.
3. A technician measures 240 volts across the two supply conductors
feeding a single-phase compressor, but the compressor will not start.
What should be checked next?
A. Outdoor humidity
B. Compressor capacitor and electrical components
C. Evaporator drain slope
D. Refrigerant cylinder temperature
Answer: B
Rationale: Correct supply voltage does not prove that starting
components are functioning; the capacitor, contactor, and compressor
circuit require further testing.
4. A homeowner reports that several rooms remain uncomfortable
even though the central air conditioner runs continuously during hot
weather. Which measurement is most useful initially?
A. Refrigerant cylinder weight
B. Supply and return air temperatures
C. Compressor oil color
D. Outdoor thermostat setting
Answer: B
,Rationale: Comparing return and supply temperatures helps determine
whether the system is producing appropriate cooling before
investigating distribution or capacity issues.
5. Before opening a refrigeration circuit for component replacement,
which procedure is essential for protecting both the technician and the
environment?
A. Vent refrigerant outdoors
B. Recover refrigerant using approved equipment
C. Increase system pressure
D. Remove the compressor oil
Answer: B
Rationale: Refrigerant must be properly recovered with approved
equipment rather than intentionally released, consistent with safe
refrigerant-handling practices.
6. A furnace technician discovers that a gas furnace produces ignition
but the burners shut down shortly afterward. Which component
commonly confirms flame presence?
A. Evaporator thermistor
B. Flame sensor
C. Liquid-line filter
D. Condenser fan blade
Answer: B
Rationale: The flame sensor verifies burner flame to the control
system; a dirty or defective sensor can cause the burners to shut down.
, 7. When measuring electrical resistance across a compressor winding,
why must electrical power be disconnected before using an ohmmeter?
A. Resistance cannot be measured indoors
B. Voltage can damage the meter and create a shock hazard
C. Refrigerant pressure will increase
D. The compressor must remain energized
Answer: B
Rationale: Ohmmeters supply their own testing voltage and should
never be connected to an energized circuit because equipment and
personnel can be endangered.
8. A properly charged cooling system has significantly reduced airflow
across the evaporator because the blower filter is heavily restricted.
What condition could eventually develop?
A. Excessive evaporator temperature
B. Evaporator coil icing
C. Increased condenser airflow
D. Reduced compressor current from improved cooling
Answer: B
Rationale: Restricted airflow can lower evaporator temperature
sufficiently for moisture to freeze on the coil, reducing airflow even
further.
