Delaware DE Class A Air Conditioning Exam
**Question 1.** Which law of thermodynamics states that energy cannot be
created or destroyed, only transferred or converted?
A) Zeroth Law
B) First Law
C) Second Law
D) Third Law
Answer: B
Explanation: The First Law of Thermodynamics is the principle of conservation of
energy, indicating that total energy in a closed system remains constant.
**Question 2.** In an air‑conditioning system, the component that removes heat
from the refrigerant by transferring it to the outdoor air is the:
A) Evaporator coil
B) Compressor
C) Condenser coil
D) Expansion valve
Answer: C
Explanation: The condenser coil releases heat absorbed in the evaporator to the
ambient environment, completing the refrigeration cycle.
**Question 3.** The temperature at which water vapor in the air begins to
condense is called the:
A) Dry‑bulb temperature
, Delaware DE Class A Air Conditioning Exam
B) Wet‑bulb temperature
C) Dew‑point temperature
D) Saturation temperature
Answer: C
Explanation: Dew‑point temperature is the point at which the air becomes
saturated and water vapor condenses into liquid.
**Question 4.** Which psychrometric property is measured directly with a sling
psychrometer?
A) Relative humidity
B) Specific volume
C) Enthalpy
D) Moisture content
Answer: A
Explanation: A sling psychrometer provides dry‑bulb and wet‑bulb readings, from
which relative humidity can be calculated.
**Question 5.** Superheat in a refrigeration system is measured at which point?
A) After the condenser
B) At the compressor inlet
C) At the evaporator outlet
D) At the expansion device outlet
, Delaware DE Class A Air Conditioning Exam
Answer: B
Explanation: Superheat is the temperature difference between the refrigerant gas
temperature at the compressor inlet and its saturation temperature at the same
pressure.
**Question 6.** A scroll compressor is preferred over a reciprocating compressor
in many residential systems because it:
A) Has higher oil consumption
B) Produces more vibration
C) Offers higher efficiency and smoother operation
D) Requires more maintenance
Answer: C
Explanation: Scroll compressors provide continuous compression with fewer
moving parts, resulting in higher efficiency and less vibration.
**Question 7.** The purpose of a TXV (Thermostatic Expansion Valve) is to:
A) Control refrigerant flow based on evaporator load
B) Increase system pressure
C) Reduce compressor speed
D) Provide a fixed metering rate
Answer: A
Explanation: A TXV adjusts the refrigerant flow to maintain a constant superheat,
matching the evaporator load.
, Delaware DE Class A Air Conditioning Exam
**Question 8.** According to the International Mechanical Code (IMC), the
minimum clearance between a condensers’ fan guard and any combustible
material is:
A) 12 inches
B) 6 inches
C) 3 inches
D) 24 inches
Answer: B
Explanation: The IMC requires at least 6 in. clearance to prevent fire hazards from
hot surfaces.
**Question 9.** In a split‑system air conditioner, the indoor unit is typically
installed:
A) In the attic only
B) In a conditioned space at a height of 6‑8 ft above the floor
C) Directly on the roof
D) Inside the mechanical room
Answer: B
Explanation: Indoor units are mounted on interior walls at a height that promotes
proper airflow and accessibility for service.
**Question 1.** Which law of thermodynamics states that energy cannot be
created or destroyed, only transferred or converted?
A) Zeroth Law
B) First Law
C) Second Law
D) Third Law
Answer: B
Explanation: The First Law of Thermodynamics is the principle of conservation of
energy, indicating that total energy in a closed system remains constant.
**Question 2.** In an air‑conditioning system, the component that removes heat
from the refrigerant by transferring it to the outdoor air is the:
A) Evaporator coil
B) Compressor
C) Condenser coil
D) Expansion valve
Answer: C
Explanation: The condenser coil releases heat absorbed in the evaporator to the
ambient environment, completing the refrigeration cycle.
**Question 3.** The temperature at which water vapor in the air begins to
condense is called the:
A) Dry‑bulb temperature
, Delaware DE Class A Air Conditioning Exam
B) Wet‑bulb temperature
C) Dew‑point temperature
D) Saturation temperature
Answer: C
Explanation: Dew‑point temperature is the point at which the air becomes
saturated and water vapor condenses into liquid.
**Question 4.** Which psychrometric property is measured directly with a sling
psychrometer?
A) Relative humidity
B) Specific volume
C) Enthalpy
D) Moisture content
Answer: A
Explanation: A sling psychrometer provides dry‑bulb and wet‑bulb readings, from
which relative humidity can be calculated.
**Question 5.** Superheat in a refrigeration system is measured at which point?
A) After the condenser
B) At the compressor inlet
C) At the evaporator outlet
D) At the expansion device outlet
, Delaware DE Class A Air Conditioning Exam
Answer: B
Explanation: Superheat is the temperature difference between the refrigerant gas
temperature at the compressor inlet and its saturation temperature at the same
pressure.
**Question 6.** A scroll compressor is preferred over a reciprocating compressor
in many residential systems because it:
A) Has higher oil consumption
B) Produces more vibration
C) Offers higher efficiency and smoother operation
D) Requires more maintenance
Answer: C
Explanation: Scroll compressors provide continuous compression with fewer
moving parts, resulting in higher efficiency and less vibration.
**Question 7.** The purpose of a TXV (Thermostatic Expansion Valve) is to:
A) Control refrigerant flow based on evaporator load
B) Increase system pressure
C) Reduce compressor speed
D) Provide a fixed metering rate
Answer: A
Explanation: A TXV adjusts the refrigerant flow to maintain a constant superheat,
matching the evaporator load.
, Delaware DE Class A Air Conditioning Exam
**Question 8.** According to the International Mechanical Code (IMC), the
minimum clearance between a condensers’ fan guard and any combustible
material is:
A) 12 inches
B) 6 inches
C) 3 inches
D) 24 inches
Answer: B
Explanation: The IMC requires at least 6 in. clearance to prevent fire hazards from
hot surfaces.
**Question 9.** In a split‑system air conditioner, the indoor unit is typically
installed:
A) In the attic only
B) In a conditioned space at a height of 6‑8 ft above the floor
C) Directly on the roof
D) Inside the mechanical room
Answer: B
Explanation: Indoor units are mounted on interior walls at a height that promotes
proper airflow and accessibility for service.
