Louisiana 640-LA – Second Class Stationary Air Conditioning
1. What is the primary function of a stationary air conditioning system?
A. Remove humidity only
B. Control temperature, humidity, air cleanliness, and circulation
C. Provide ventilation only
D. Produce refrigeration exclusively
ANSWER : B
Explanation:
Stationary AC systems are designed to control temperature, humidity, air
quality, and airflow for occupant comfort and equipment protection.
2. Which refrigeration cycle component increases refrigerant pressure and
temperature?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
ANSWER : C
Explanation:
The compressor raises refrigerant pressure and temperature, allowing heat
rejection in the condenser.
3. In a vapor compression system, the evaporator absorbs heat by:
A. Condensing refrigerant
B. Compressing refrigerant
,C. Evaporating refrigerant
D. Expanding refrigerant vapor
ANSWER : C
Explanation:
Liquid refrigerant absorbs heat and evaporates, cooling the surrounding air or
water.
4. Which refrigerant is most commonly used in older stationary AC
systems?
A. R-22
B. R-717
C. R-744
D. R-410A
ANSWER : A
Explanation:
R-22 was widely used historically, though now phased out due to ozone
depletion regulations.
5. What is the primary purpose of superheating refrigerant vapor?
A. Increase cooling capacity
B. Prevent liquid refrigerant from entering the compressor
C. Reduce system pressure
D. Increase condenser efficiency
ANSWER : B
Explanation:
Superheat ensures only vapor enters the compressor, preventing mechanical
damage.
6. What device meters refrigerant flow into the evaporator?
A. Compressor
B. Receiver
C. Expansion valve
D. Condenser fan
,ANSWER : C
Explanation:
The expansion valve regulates refrigerant flow and maintains proper superheat.
7. Which instrument measures system pressure?
A. Thermometer
B. Anemometer
C. Manifold gauge
D. Hygrometer
ANSWER : C
Explanation:
Manifold gauges measure high- and low-side refrigerant pressures.
8. High condenser pressure is most commonly caused by:
A. Low refrigerant charge
B. Dirty condenser coils
C. Low ambient temperature
D. Restricted evaporator airflow
ANSWER : B
Explanation:
Dirty coils reduce heat rejection, increasing condenser pressure.
9. What happens if an evaporator coil freezes?
A. Increased cooling capacity
B. Reduced airflow and heat transfer
C. Increased system efficiency
D. Higher superheat
ANSWER : B
Explanation:
Ice blocks airflow and insulation reduces heat absorption.
, 10. Which electrical component protects motors from overload?
A. Contactor
B. Relay
C. Overload protector
D. Transformer
ANSWER : C
Explanation:
Overload protectors prevent motor overheating and damage.
11. What type of motor is most commonly used in large stationary AC
compressors?
A. Universal motor
B. DC motor
C. Induction motor
D. Stepper motor
ANSWER : C
Explanation:
Induction motors are durable and efficient for stationary applications.
12. What is the function of a condenser fan?
A. Cool the compressor
B. Move air across condenser coils
C. Increase refrigerant pressure
D. Control refrigerant flow
ANSWER : B
Explanation:
The condenser fan removes heat by moving air across the coils.
13. Which safety device shuts down the system if pressure is excessive?
A. Thermostat
B. Low-pressure switch
1. What is the primary function of a stationary air conditioning system?
A. Remove humidity only
B. Control temperature, humidity, air cleanliness, and circulation
C. Provide ventilation only
D. Produce refrigeration exclusively
ANSWER : B
Explanation:
Stationary AC systems are designed to control temperature, humidity, air
quality, and airflow for occupant comfort and equipment protection.
2. Which refrigeration cycle component increases refrigerant pressure and
temperature?
A. Evaporator
B. Condenser
C. Compressor
D. Expansion valve
ANSWER : C
Explanation:
The compressor raises refrigerant pressure and temperature, allowing heat
rejection in the condenser.
3. In a vapor compression system, the evaporator absorbs heat by:
A. Condensing refrigerant
B. Compressing refrigerant
,C. Evaporating refrigerant
D. Expanding refrigerant vapor
ANSWER : C
Explanation:
Liquid refrigerant absorbs heat and evaporates, cooling the surrounding air or
water.
4. Which refrigerant is most commonly used in older stationary AC
systems?
A. R-22
B. R-717
C. R-744
D. R-410A
ANSWER : A
Explanation:
R-22 was widely used historically, though now phased out due to ozone
depletion regulations.
5. What is the primary purpose of superheating refrigerant vapor?
A. Increase cooling capacity
B. Prevent liquid refrigerant from entering the compressor
C. Reduce system pressure
D. Increase condenser efficiency
ANSWER : B
Explanation:
Superheat ensures only vapor enters the compressor, preventing mechanical
damage.
6. What device meters refrigerant flow into the evaporator?
A. Compressor
B. Receiver
C. Expansion valve
D. Condenser fan
,ANSWER : C
Explanation:
The expansion valve regulates refrigerant flow and maintains proper superheat.
7. Which instrument measures system pressure?
A. Thermometer
B. Anemometer
C. Manifold gauge
D. Hygrometer
ANSWER : C
Explanation:
Manifold gauges measure high- and low-side refrigerant pressures.
8. High condenser pressure is most commonly caused by:
A. Low refrigerant charge
B. Dirty condenser coils
C. Low ambient temperature
D. Restricted evaporator airflow
ANSWER : B
Explanation:
Dirty coils reduce heat rejection, increasing condenser pressure.
9. What happens if an evaporator coil freezes?
A. Increased cooling capacity
B. Reduced airflow and heat transfer
C. Increased system efficiency
D. Higher superheat
ANSWER : B
Explanation:
Ice blocks airflow and insulation reduces heat absorption.
, 10. Which electrical component protects motors from overload?
A. Contactor
B. Relay
C. Overload protector
D. Transformer
ANSWER : C
Explanation:
Overload protectors prevent motor overheating and damage.
11. What type of motor is most commonly used in large stationary AC
compressors?
A. Universal motor
B. DC motor
C. Induction motor
D. Stepper motor
ANSWER : C
Explanation:
Induction motors are durable and efficient for stationary applications.
12. What is the function of a condenser fan?
A. Cool the compressor
B. Move air across condenser coils
C. Increase refrigerant pressure
D. Control refrigerant flow
ANSWER : B
Explanation:
The condenser fan removes heat by moving air across the coils.
13. Which safety device shuts down the system if pressure is excessive?
A. Thermostat
B. Low-pressure switch
