1) Which refrigerant is commonly used in modern residential systems in
Wisconsin?
A) R-22
B) R-410A
C) R-134a
D) R-12
ANSWER : B) R-410A
Explanation: R-410A replaced R-22 due to higher efficiency and
ozone-friendly properties; R-22 is being phased out.
2) What is the primary purpose of a TXV (Thermostatic Expansion
Valve)?
A) Increase system pressure
B) Regulate refrigerant flow into evaporator
C) Measure temperature in compressor
D) Heat refrigerant
ANSWER : B) Regulate refrigerant flow into evaporator
Explanation: TXV controls the amount of refrigerant entering the evaporator to
maintain proper superheat and efficiency.
3) Low refrigerant in a system causes:
A) High suction pressure
B) Reduced cooling capacity
C) Compressor overload protection to trip
D) Both B and C
ANSWER : D) Both B and C
Explanation: Low refrigerant reduces cooling and can cause overheating of the
compressor, tripping safety controls.
4) What is the safe way to handle refrigerants like R-410A?
A) Use any HVAC gauge set
B) Use EPA-approved recovery equipment
,C) Vent into the atmosphere
D) Mix with air to dilute
ANSWER : B) Use EPA-approved recovery equipment
Explanation: EPA regulations require proper recovery to prevent ozone
depletion and greenhouse effects.
5) The dew point of air is the:
A) Temperature at which water vapor condenses
B) Temperature of the wet bulb
C) Temperature of the dry bulb
D) Pressure of the refrigerant
ANSWER : A) Temperature at which water vapor condenses
Explanation: Dew point is critical for sizing dehumidification and controlling
condensation in HVAC systems.
Category: Electrical & Controls
6) What is the standard voltage for a residential split-system HVAC unit in
Wisconsin?
A) 110–120V
B) 208–230V
C) 460V
D) 12V
ANSWER : B) 208–230V
Explanation: Most residential HVAC units use 208–230V single-phase power;
110–120V is usually for controls.
7) A contactor in an HVAC system:
A) Pumps refrigerant
B) Opens or closes electrical circuits
C) Measures temperature
D) Controls airflow
ANSWER : B) Opens or closes electrical circuits
Explanation: The contactor switches power to the compressor or condenser fan
based on thermostat signals.
8) What does a capacitor do in an HVAC motor?
A) Stores refrigerant
B) Stores electrical energy to start or run the motor
C) Measures voltage
D) Opens circuits
, ANSWER : B) Stores electrical energy to start or run the motor
Explanation: Capacitors provide the extra torque needed to start motors and
help maintain efficiency.
9) Which color is typically used for a 24V “R” wire in thermostat wiring?
A) Red
B) Blue
C) Yellow
D) Green
ANSWER : A) Red
Explanation: “R” is the 24V hot wire supplying the thermostat; common color
standard in residential systems.
10) What is the purpose of a limit switch in a furnace?
A) Control refrigerant flow
B) Turn off burners if temperatures exceed safe limits
C) Start blower fan
D) Measure pressure
ANSWER : B) Turn off burners if temperatures exceed safe limits
Explanation: Limit switches prevent overheating, protecting the furnace and
home from damage.
Category: Airflow & Ducting
11) Standard residential duct velocity should not exceed:
A) 500 FPM
B) 700 FPM
C) 1200 FPM
D) 2000 FPM
ANSWER : C) 1200 FPM
Explanation: Keeping velocity under 1200 FPM reduces noise and friction loss
in ducts.
12) What is the primary purpose of a return air duct?
A) Deliver conditioned air to rooms
B) Remove air from rooms and return it to the HVAC system
C) Supply fresh outside air
D) Circulate refrigerant
ANSWER : B) Remove air from rooms and return it to the HVAC system
Explanation: Return ducts maintain system efficiency and proper pressure
balance.
, 13) Static pressure in a duct system is measured in:
A) Volts
B) PSI
C) Inches of water column (in. w.c.)
D) Hertz
ANSWER : C) Inches of water column (in. w.c.)
Explanation: Static pressure measures resistance in ducts; critical for airflow
calculations.
14) Undersized ducts can cause:
A) Noise
B) Poor airflow
C) Higher energy consumption
D) All of the above
ANSWER : D) All of the above
Explanation: Undersized ducts increase velocity, create noise, reduce comfort,
and increase system load.
15) A plenum is:
A) A type of refrigerant line
B) A chamber used to distribute air in ductwork
C) A type of compressor
D) A filter
ANSWER : B) A chamber used to distribute air in ductwork
Explanation: Plenums connect HVAC units to duct systems and help evenly
distribute conditioned air.
16) What is the function of a balancing damper in ductwork?
A) Increase refrigerant pressure
B) Control and balance airflow in the system
C) Reduce electrical load
D) Measure static pressure
ANSWER : B) Control and balance airflow in the system
Explanation: Dampers adjust airflow to rooms to achieve uniform temperature
distribution.
17) What can cause a drop in system airflow besides undersized ducts?
A) Dirty air filters
B) Closed dampers
C) Obstructed registers
D) All of the above
ANSWER : D) All of the above
Wisconsin?
A) R-22
B) R-410A
C) R-134a
D) R-12
ANSWER : B) R-410A
Explanation: R-410A replaced R-22 due to higher efficiency and
ozone-friendly properties; R-22 is being phased out.
2) What is the primary purpose of a TXV (Thermostatic Expansion
Valve)?
A) Increase system pressure
B) Regulate refrigerant flow into evaporator
C) Measure temperature in compressor
D) Heat refrigerant
ANSWER : B) Regulate refrigerant flow into evaporator
Explanation: TXV controls the amount of refrigerant entering the evaporator to
maintain proper superheat and efficiency.
3) Low refrigerant in a system causes:
A) High suction pressure
B) Reduced cooling capacity
C) Compressor overload protection to trip
D) Both B and C
ANSWER : D) Both B and C
Explanation: Low refrigerant reduces cooling and can cause overheating of the
compressor, tripping safety controls.
4) What is the safe way to handle refrigerants like R-410A?
A) Use any HVAC gauge set
B) Use EPA-approved recovery equipment
,C) Vent into the atmosphere
D) Mix with air to dilute
ANSWER : B) Use EPA-approved recovery equipment
Explanation: EPA regulations require proper recovery to prevent ozone
depletion and greenhouse effects.
5) The dew point of air is the:
A) Temperature at which water vapor condenses
B) Temperature of the wet bulb
C) Temperature of the dry bulb
D) Pressure of the refrigerant
ANSWER : A) Temperature at which water vapor condenses
Explanation: Dew point is critical for sizing dehumidification and controlling
condensation in HVAC systems.
Category: Electrical & Controls
6) What is the standard voltage for a residential split-system HVAC unit in
Wisconsin?
A) 110–120V
B) 208–230V
C) 460V
D) 12V
ANSWER : B) 208–230V
Explanation: Most residential HVAC units use 208–230V single-phase power;
110–120V is usually for controls.
7) A contactor in an HVAC system:
A) Pumps refrigerant
B) Opens or closes electrical circuits
C) Measures temperature
D) Controls airflow
ANSWER : B) Opens or closes electrical circuits
Explanation: The contactor switches power to the compressor or condenser fan
based on thermostat signals.
8) What does a capacitor do in an HVAC motor?
A) Stores refrigerant
B) Stores electrical energy to start or run the motor
C) Measures voltage
D) Opens circuits
, ANSWER : B) Stores electrical energy to start or run the motor
Explanation: Capacitors provide the extra torque needed to start motors and
help maintain efficiency.
9) Which color is typically used for a 24V “R” wire in thermostat wiring?
A) Red
B) Blue
C) Yellow
D) Green
ANSWER : A) Red
Explanation: “R” is the 24V hot wire supplying the thermostat; common color
standard in residential systems.
10) What is the purpose of a limit switch in a furnace?
A) Control refrigerant flow
B) Turn off burners if temperatures exceed safe limits
C) Start blower fan
D) Measure pressure
ANSWER : B) Turn off burners if temperatures exceed safe limits
Explanation: Limit switches prevent overheating, protecting the furnace and
home from damage.
Category: Airflow & Ducting
11) Standard residential duct velocity should not exceed:
A) 500 FPM
B) 700 FPM
C) 1200 FPM
D) 2000 FPM
ANSWER : C) 1200 FPM
Explanation: Keeping velocity under 1200 FPM reduces noise and friction loss
in ducts.
12) What is the primary purpose of a return air duct?
A) Deliver conditioned air to rooms
B) Remove air from rooms and return it to the HVAC system
C) Supply fresh outside air
D) Circulate refrigerant
ANSWER : B) Remove air from rooms and return it to the HVAC system
Explanation: Return ducts maintain system efficiency and proper pressure
balance.
, 13) Static pressure in a duct system is measured in:
A) Volts
B) PSI
C) Inches of water column (in. w.c.)
D) Hertz
ANSWER : C) Inches of water column (in. w.c.)
Explanation: Static pressure measures resistance in ducts; critical for airflow
calculations.
14) Undersized ducts can cause:
A) Noise
B) Poor airflow
C) Higher energy consumption
D) All of the above
ANSWER : D) All of the above
Explanation: Undersized ducts increase velocity, create noise, reduce comfort,
and increase system load.
15) A plenum is:
A) A type of refrigerant line
B) A chamber used to distribute air in ductwork
C) A type of compressor
D) A filter
ANSWER : B) A chamber used to distribute air in ductwork
Explanation: Plenums connect HVAC units to duct systems and help evenly
distribute conditioned air.
16) What is the function of a balancing damper in ductwork?
A) Increase refrigerant pressure
B) Control and balance airflow in the system
C) Reduce electrical load
D) Measure static pressure
ANSWER : B) Control and balance airflow in the system
Explanation: Dampers adjust airflow to rooms to achieve uniform temperature
distribution.
17) What can cause a drop in system airflow besides undersized ducts?
A) Dirty air filters
B) Closed dampers
C) Obstructed registers
D) All of the above
ANSWER : D) All of the above
