DC HVAC Systems Installer Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. Which of the following is the primary purpose of a Manual J load
calculation before installing an HVAC system?
A. Determine the brand of equipment to purchase
B. Calculate the heating and cooling requirements of the building
C. Determine the duct material thickness only
D. Estimate annual maintenance costs only
Rationale: Manual J calculations determine the heating and cooling loads
of a building based on insulation, occupancy, windows, orientation, and
climate. Proper sizing improves comfort, efficiency, and equipment
lifespan.
2. What is the primary function of an evaporator coil in an air
conditioning system?
A. Reject heat to the outdoors
B. Compress refrigerant vapor
C. Absorb heat from indoor air
D. Store liquid refrigerant
,Rationale: The evaporator coil absorbs heat from indoor air as refrigerant
evaporates, producing the cooling effect delivered throughout the
conditioned space.
3. Which refrigerant component raises the pressure and temperature of
refrigerant vapor?
A. Condenser
B. Expansion valve
C. Compressor
D. Receiver-drier
Rationale: The compressor pumps refrigerant through the system while
increasing its pressure and temperature, enabling heat rejection at the
condenser.
4. What device meters refrigerant into the evaporator?
A. Compressor
B. Condenser fan
C. Thermal expansion valve (TXV) or metering device
D. Suction accumulator
Rationale: The metering device controls refrigerant flow into the
evaporator while creating the pressure drop necessary for refrigeration.
5. Why is proper airflow across an evaporator coil important?
A. To reduce refrigerant pressure
B. To increase compressor noise
C. To ensure efficient heat transfer and prevent coil freezing
D. To eliminate condensate drainage
Rationale: Insufficient airflow reduces heat transfer, leading to poor
cooling, frozen coils, and compressor damage.
, 6. Which instrument measures refrigerant system pressures?
A. Clamp ammeter
B. Manifold gauge set
C. Anemometer
D. Combustion analyzer
Rationale: A manifold gauge set measures high-side and low-side
refrigerant pressures during installation, servicing, and troubleshooting.
7. What is the purpose of pulling a deep vacuum before charging a
refrigeration system?
A. Increase refrigerant temperature
B. Lubricate compressor bearings
C. Remove air and moisture from the system
D. Raise operating pressure
Rationale: Evacuation removes non-condensable gases and moisture,
preventing corrosion, acid formation, and poor system performance.
8. Which EPA certification is required to handle most refrigerants in HVAC
systems?
A. OSHA 30
B. NATE
C. EPA Section 608 Certification
D. ICC Residential Certification
Rationale: EPA Section 608 certification is federally required for technicians
handling regulated refrigerants.
9. Which refrigerant line is typically insulated?
A. Liquid line
B. Suction line
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. Which of the following is the primary purpose of a Manual J load
calculation before installing an HVAC system?
A. Determine the brand of equipment to purchase
B. Calculate the heating and cooling requirements of the building
C. Determine the duct material thickness only
D. Estimate annual maintenance costs only
Rationale: Manual J calculations determine the heating and cooling loads
of a building based on insulation, occupancy, windows, orientation, and
climate. Proper sizing improves comfort, efficiency, and equipment
lifespan.
2. What is the primary function of an evaporator coil in an air
conditioning system?
A. Reject heat to the outdoors
B. Compress refrigerant vapor
C. Absorb heat from indoor air
D. Store liquid refrigerant
,Rationale: The evaporator coil absorbs heat from indoor air as refrigerant
evaporates, producing the cooling effect delivered throughout the
conditioned space.
3. Which refrigerant component raises the pressure and temperature of
refrigerant vapor?
A. Condenser
B. Expansion valve
C. Compressor
D. Receiver-drier
Rationale: The compressor pumps refrigerant through the system while
increasing its pressure and temperature, enabling heat rejection at the
condenser.
4. What device meters refrigerant into the evaporator?
A. Compressor
B. Condenser fan
C. Thermal expansion valve (TXV) or metering device
D. Suction accumulator
Rationale: The metering device controls refrigerant flow into the
evaporator while creating the pressure drop necessary for refrigeration.
5. Why is proper airflow across an evaporator coil important?
A. To reduce refrigerant pressure
B. To increase compressor noise
C. To ensure efficient heat transfer and prevent coil freezing
D. To eliminate condensate drainage
Rationale: Insufficient airflow reduces heat transfer, leading to poor
cooling, frozen coils, and compressor damage.
, 6. Which instrument measures refrigerant system pressures?
A. Clamp ammeter
B. Manifold gauge set
C. Anemometer
D. Combustion analyzer
Rationale: A manifold gauge set measures high-side and low-side
refrigerant pressures during installation, servicing, and troubleshooting.
7. What is the purpose of pulling a deep vacuum before charging a
refrigeration system?
A. Increase refrigerant temperature
B. Lubricate compressor bearings
C. Remove air and moisture from the system
D. Raise operating pressure
Rationale: Evacuation removes non-condensable gases and moisture,
preventing corrosion, acid formation, and poor system performance.
8. Which EPA certification is required to handle most refrigerants in HVAC
systems?
A. OSHA 30
B. NATE
C. EPA Section 608 Certification
D. ICC Residential Certification
Rationale: EPA Section 608 certification is federally required for technicians
handling regulated refrigerants.
9. Which refrigerant line is typically insulated?
A. Liquid line
B. Suction line
