NATE Core Service Certification Exam
With Actual Questions & Verified
Answers, Plus Explained
Rationales/Expert Verified For
Guaranteed Pass 2026/Latest
Updated/Instant Download Pdf
1. Which of the following is the primary purpose of a heat exchanger
in an HVAC system?
A. Increase refrigerant pressure
B. Transfer heat between two fluids
C. Control airflow velocity
D. Reduce electrical consumption
B. Transfer heat between two fluids
Rationale: A heat exchanger is designed to efficiently transfer heat
from one fluid (air, water, or refrigerant) to another without mixing
them.
2. What is the most common type of airflow measurement used in
residential HVAC systems?
A. Static pressure
B. Velocity pressure
C. Cubic feet per minute (CFM)
D. Temperature differential
,C. Cubic feet per minute (CFM)
Rationale: CFM measures the volume of air moving through a system,
which is essential for sizing and balancing ductwork.
3. Which safety device shuts off a gas furnace if the flame goes out?
A. Pressure switch
B. Flame sensor
C. High-limit switch
D. Thermostat
B. Flame sensor
Rationale: The flame sensor detects whether the burner flame is
present and shuts off the gas to prevent unsafe gas buildup.
4. What is the function of a capacitor in an electric motor?
A. Store refrigerant
B. Increase torque and efficiency
C. Measure airflow
D. Reduce noise
B. Increase torque and efficiency
Rationale: Capacitors provide a phase shift that helps start and run
single-phase motors more efficiently.
5. Which type of refrigerant is considered an HFC?
A. R-22
B. R-134a
C. R-123
D. Ammonia
B. R-134a
Rationale: HFCs (Hydrofluorocarbons) like R-134a do not contain
chlorine, unlike HCFCs.
, 6. What is the purpose of the high-limit switch in a furnace?
A. Shut down the fan
B. Prevent overheating
C. Detect flame
D. Control fuel pressure
B. Prevent overheating
Rationale: The high-limit switch opens the circuit to the burner if the
furnace exceeds a safe temperature.
7. What is the primary reason for performing a duct leakage test?
A. Check refrigerant charge
B. Identify airflow losses
C. Test thermostat calibration
D. Measure coil efficiency
B. Identify airflow losses
Rationale: Leaky ducts reduce system efficiency and comfort, and a
leakage test helps identify problem areas.
8. What is the first step in troubleshooting an HVAC system?
A. Replace parts
B. Measure airflow
C. Verify the complaint and gather data
D. Adjust refrigerant charge
C. Verify the complaint and gather data
Rationale: Proper troubleshooting starts with understanding the
customer’s concern and gathering system information before taking
action.
9. What type of current does a standard residential HVAC system
use?
A. Direct current (DC)
, B. Alternating current (AC)
C. Three-phase DC
D. High-voltage DC
B. Alternating current (AC)
Rationale: Residential HVAC systems operate on AC power supplied by
the utility for motors and controls.
10. What is the main purpose of a condensate drain in an air
conditioning system?
A. Reduce refrigerant pressure
B. Remove condensed water
C. Increase airflow
D. Support the evaporator coil
B. Remove condensed water
Rationale: Condensate drains remove moisture that condenses on the
evaporator coil during cooling to prevent water damage.
11. Which of the following tools is used to measure superheat?
A. Manometer
B. Thermometer and pressure gauge
C. Multimeter
D. Anemometer
B. Thermometer and pressure gauge
Rationale: Superheat is calculated using the suction line temperature
and pressure to ensure correct refrigerant charge.
12. Which component controls the flow of refrigerant into the
evaporator?
A. Expansion valve
B. Compressor
With Actual Questions & Verified
Answers, Plus Explained
Rationales/Expert Verified For
Guaranteed Pass 2026/Latest
Updated/Instant Download Pdf
1. Which of the following is the primary purpose of a heat exchanger
in an HVAC system?
A. Increase refrigerant pressure
B. Transfer heat between two fluids
C. Control airflow velocity
D. Reduce electrical consumption
B. Transfer heat between two fluids
Rationale: A heat exchanger is designed to efficiently transfer heat
from one fluid (air, water, or refrigerant) to another without mixing
them.
2. What is the most common type of airflow measurement used in
residential HVAC systems?
A. Static pressure
B. Velocity pressure
C. Cubic feet per minute (CFM)
D. Temperature differential
,C. Cubic feet per minute (CFM)
Rationale: CFM measures the volume of air moving through a system,
which is essential for sizing and balancing ductwork.
3. Which safety device shuts off a gas furnace if the flame goes out?
A. Pressure switch
B. Flame sensor
C. High-limit switch
D. Thermostat
B. Flame sensor
Rationale: The flame sensor detects whether the burner flame is
present and shuts off the gas to prevent unsafe gas buildup.
4. What is the function of a capacitor in an electric motor?
A. Store refrigerant
B. Increase torque and efficiency
C. Measure airflow
D. Reduce noise
B. Increase torque and efficiency
Rationale: Capacitors provide a phase shift that helps start and run
single-phase motors more efficiently.
5. Which type of refrigerant is considered an HFC?
A. R-22
B. R-134a
C. R-123
D. Ammonia
B. R-134a
Rationale: HFCs (Hydrofluorocarbons) like R-134a do not contain
chlorine, unlike HCFCs.
, 6. What is the purpose of the high-limit switch in a furnace?
A. Shut down the fan
B. Prevent overheating
C. Detect flame
D. Control fuel pressure
B. Prevent overheating
Rationale: The high-limit switch opens the circuit to the burner if the
furnace exceeds a safe temperature.
7. What is the primary reason for performing a duct leakage test?
A. Check refrigerant charge
B. Identify airflow losses
C. Test thermostat calibration
D. Measure coil efficiency
B. Identify airflow losses
Rationale: Leaky ducts reduce system efficiency and comfort, and a
leakage test helps identify problem areas.
8. What is the first step in troubleshooting an HVAC system?
A. Replace parts
B. Measure airflow
C. Verify the complaint and gather data
D. Adjust refrigerant charge
C. Verify the complaint and gather data
Rationale: Proper troubleshooting starts with understanding the
customer’s concern and gathering system information before taking
action.
9. What type of current does a standard residential HVAC system
use?
A. Direct current (DC)
, B. Alternating current (AC)
C. Three-phase DC
D. High-voltage DC
B. Alternating current (AC)
Rationale: Residential HVAC systems operate on AC power supplied by
the utility for motors and controls.
10. What is the main purpose of a condensate drain in an air
conditioning system?
A. Reduce refrigerant pressure
B. Remove condensed water
C. Increase airflow
D. Support the evaporator coil
B. Remove condensed water
Rationale: Condensate drains remove moisture that condenses on the
evaporator coil during cooling to prevent water damage.
11. Which of the following tools is used to measure superheat?
A. Manometer
B. Thermometer and pressure gauge
C. Multimeter
D. Anemometer
B. Thermometer and pressure gauge
Rationale: Superheat is calculated using the suction line temperature
and pressure to ensure correct refrigerant charge.
12. Which component controls the flow of refrigerant into the
evaporator?
A. Expansion valve
B. Compressor
