1. Which of the following is the primary refrigerant used in most new
residential air conditioning systems after R-22 phaseout?
A. R-12
B. R-134a
C. R-410A
D. R-123
Answer: C. R-410A
Explanation: R-410A replaced R-22 in most residential applications due to its
zero ozone depletion potential and compliance with EPA regulations.
2. In Nevada, the C-21B license specifically covers work in:
A. Refrigeration only
B. Heating, cooling, and ventilation systems
C. Plumbing installation
D. Electrical panel installation
Answer: B. Heating, cooling, and ventilation systems
Explanation: The C-21B scope is limited to installing and servicing air
conditioning, refrigeration, and ventilation systems, excluding unrelated trades
like plumbing or main electrical service work.
3. The term SEER refers to:
A. Seasonal Energy Efficiency Ratio
B. Standard Electrical Equipment Rating
C. Seasonal Electrical Efficiency Rate
D. Standard Energy Evaluation Report
Answer: A. Seasonal Energy Efficiency Ratio
Explanation: SEER measures the cooling output during a typical cooling
season divided by the total electric energy input.
,4. What is the minimum SEER rating required for new central AC units in
Nevada as of 2023?
A. 10
B. 13
C. 14
D. 16
Answer: C. 14
Explanation: Federal regulations require at least 14 SEER for split-system
central ACs in the Southwest region, which includes Nevada.
5. The correct tool to measure superheat is:
A. Voltmeter
B. Ammeter
C. Thermometer and pressure gauge
D. Multimeter with ohms setting
Answer: C. Thermometer and pressure gauge
Explanation: Superheat is calculated using the measured suction line
temperature and corresponding saturation temperature from a pressure reading.
6. A low superheat reading typically indicates:
A. Overcharged system
B. Undercharged system
C. Flooded evaporator
D. Restriction in liquid line
Answer: C. Flooded evaporator
Explanation: Low superheat means liquid refrigerant is not being fully
vaporized in the evaporator, often caused by overfeeding.
7. In an R-410A system, high head pressure can be caused by:
A. Dirty condenser coils
B. Low ambient temperature
C. Low refrigerant charge
D. Oversized evaporator
,Answer: A. Dirty condenser coils
Explanation: Dirty coils restrict heat transfer, causing higher discharge
pressures.
8. The NEC requires the disconnect for an air conditioning condenser to be
located:
A. Anywhere inside the home
B. Within sight and readily accessible from the unit
C. In the main electrical panel
D. On the roof regardless of unit location
Answer: B. Within sight and readily accessible from the unit
Explanation: NEC 440.14 requires a disconnecting means within sight of and
readily accessible from the air conditioning equipment.
9. The most common type of motor used in residential AC blowers is:
A. Shaded pole
B. PSC (Permanent Split Capacitor)
C. Series wound
D. Stepper motor
Answer: B. PSC (Permanent Split Capacitor)
Explanation: PSC motors are efficient, quiet, and durable, making them
common in blower applications.
10. Which refrigerant cylinder color is associated with R-410A?
A. Light blue
B. Pink
C. Green
D. Orange
Answer: B. Pink
Explanation: R-410A cylinders are color-coded pink for easy identification.
11. What is the primary function of an expansion valve in an AC system?
A. Increase refrigerant temperature
, B. Maintain constant evaporator pressure
C. Regulate refrigerant flow into the evaporator
D. Control condenser fan speed
Answer: C. Regulate refrigerant flow into the evaporator
Explanation: The expansion valve meters refrigerant to match load
requirements and maintain proper superheat.
12. Which duct material is NOT recommended for outdoor use in Nevada’s
climate?
A. Sheet metal
B. Fiberglass duct board
C. Flexible insulated duct
D. PVC-coated sheet metal
Answer: B. Fiberglass duct board
Explanation: Fiberglass duct board is susceptible to moisture damage and
degradation from UV exposure.
13. What is the typical temperature drop across an evaporator coil in a properly
charged system?
A. 2–5°F
B. 10–15°F
C. 18–22°F
D. 30–35°F
Answer: C. 18–22°F
Explanation: A temperature difference of 18–22°F between return and supply
air is typical for efficient operation.
14. In Nevada, the Building Code requires condensate drains to:
A. Discharge onto walkways
B. Be directly connected to sewer lines without trap
C. Terminate to an approved location without causing nuisance
D. Discharge into storm drains
Answer: C. Terminate to an approved location without causing nuisance
Explanation: Drains must prevent water damage or safety hazards.
residential air conditioning systems after R-22 phaseout?
A. R-12
B. R-134a
C. R-410A
D. R-123
Answer: C. R-410A
Explanation: R-410A replaced R-22 in most residential applications due to its
zero ozone depletion potential and compliance with EPA regulations.
2. In Nevada, the C-21B license specifically covers work in:
A. Refrigeration only
B. Heating, cooling, and ventilation systems
C. Plumbing installation
D. Electrical panel installation
Answer: B. Heating, cooling, and ventilation systems
Explanation: The C-21B scope is limited to installing and servicing air
conditioning, refrigeration, and ventilation systems, excluding unrelated trades
like plumbing or main electrical service work.
3. The term SEER refers to:
A. Seasonal Energy Efficiency Ratio
B. Standard Electrical Equipment Rating
C. Seasonal Electrical Efficiency Rate
D. Standard Energy Evaluation Report
Answer: A. Seasonal Energy Efficiency Ratio
Explanation: SEER measures the cooling output during a typical cooling
season divided by the total electric energy input.
,4. What is the minimum SEER rating required for new central AC units in
Nevada as of 2023?
A. 10
B. 13
C. 14
D. 16
Answer: C. 14
Explanation: Federal regulations require at least 14 SEER for split-system
central ACs in the Southwest region, which includes Nevada.
5. The correct tool to measure superheat is:
A. Voltmeter
B. Ammeter
C. Thermometer and pressure gauge
D. Multimeter with ohms setting
Answer: C. Thermometer and pressure gauge
Explanation: Superheat is calculated using the measured suction line
temperature and corresponding saturation temperature from a pressure reading.
6. A low superheat reading typically indicates:
A. Overcharged system
B. Undercharged system
C. Flooded evaporator
D. Restriction in liquid line
Answer: C. Flooded evaporator
Explanation: Low superheat means liquid refrigerant is not being fully
vaporized in the evaporator, often caused by overfeeding.
7. In an R-410A system, high head pressure can be caused by:
A. Dirty condenser coils
B. Low ambient temperature
C. Low refrigerant charge
D. Oversized evaporator
,Answer: A. Dirty condenser coils
Explanation: Dirty coils restrict heat transfer, causing higher discharge
pressures.
8. The NEC requires the disconnect for an air conditioning condenser to be
located:
A. Anywhere inside the home
B. Within sight and readily accessible from the unit
C. In the main electrical panel
D. On the roof regardless of unit location
Answer: B. Within sight and readily accessible from the unit
Explanation: NEC 440.14 requires a disconnecting means within sight of and
readily accessible from the air conditioning equipment.
9. The most common type of motor used in residential AC blowers is:
A. Shaded pole
B. PSC (Permanent Split Capacitor)
C. Series wound
D. Stepper motor
Answer: B. PSC (Permanent Split Capacitor)
Explanation: PSC motors are efficient, quiet, and durable, making them
common in blower applications.
10. Which refrigerant cylinder color is associated with R-410A?
A. Light blue
B. Pink
C. Green
D. Orange
Answer: B. Pink
Explanation: R-410A cylinders are color-coded pink for easy identification.
11. What is the primary function of an expansion valve in an AC system?
A. Increase refrigerant temperature
, B. Maintain constant evaporator pressure
C. Regulate refrigerant flow into the evaporator
D. Control condenser fan speed
Answer: C. Regulate refrigerant flow into the evaporator
Explanation: The expansion valve meters refrigerant to match load
requirements and maintain proper superheat.
12. Which duct material is NOT recommended for outdoor use in Nevada’s
climate?
A. Sheet metal
B. Fiberglass duct board
C. Flexible insulated duct
D. PVC-coated sheet metal
Answer: B. Fiberglass duct board
Explanation: Fiberglass duct board is susceptible to moisture damage and
degradation from UV exposure.
13. What is the typical temperature drop across an evaporator coil in a properly
charged system?
A. 2–5°F
B. 10–15°F
C. 18–22°F
D. 30–35°F
Answer: C. 18–22°F
Explanation: A temperature difference of 18–22°F between return and supply
air is typical for efficient operation.
14. In Nevada, the Building Code requires condensate drains to:
A. Discharge onto walkways
B. Be directly connected to sewer lines without trap
C. Terminate to an approved location without causing nuisance
D. Discharge into storm drains
Answer: C. Terminate to an approved location without causing nuisance
Explanation: Drains must prevent water damage or safety hazards.
