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Texas (TX) Class B Air Conditioning and Refrigeration
Contractor Exam | Latest Verified Questions and Detailed
Answers
OVERVIEW DESCRIPTION
This Comprehensive set of multiple choice questions is designed for the Texas Class B
Air Conditioning and Refrigeration Contractor Exam, an open-book licensing test
administered by PSI. The exam evaluates technical knowledge and code compliance for
residential and light commercial HVAC/R systems with a cooling capacity up to 25 tons
or heating up to 1.5 million BTU/h. The content spans HVAC systems design (Manual J,
N, and D), refrigeration principles and components, refrigerant handling and EPA
regulations, ductwork, piping and venting, electrical and gas codes, installation and
maintenance practices, as well as business law and Texas licensing rules.
QUESTION 1
According to Manual J, what is the primary purpose of the design temperature
difference (DTD)?
A. To size ductwork
B. To calculate heat loss and gain through building envelope components
C. To determine refrigerant charge
D. To select grille sizes
CORRECT ANSWER: B
EXPERT RATIONALE: Manual J uses DTD (indoor–outdoor temperature difference) to
compute conduction heat gains/losses through walls, ceilings, and floors.
QUESTION 2
A Class B license in Texas authorizes work on air conditioning systems with a maximum
cooling capacity of:
A. 15 tons
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B. 25 tons
C. 50 tons
D. 100 tons
CORRECT ANSWER: B
EXPERT RATIONALE: The Class B endorsement is limited to 25 tons cooling and 1.5
million BTU/h heating capacity.
QUESTION 3
Manual N is used primarily for:
A. Residential heat loss calculations
B. Small commercial load calculations
C. Duct sizing for single-family homes
D. Refrigerant piping design
CORRECT ANSWER: B
EXPERT RATIONALE: Manual N provides procedures for heating and cooling load
calculations in light commercial buildings, complementing Manual J for residential.
QUESTION 4
In the basic vapor-compression refrigeration cycle, the component that absorbs heat
from the conditioned space is the:
A. Compressor
B. Condenser
C. Expansion valve
D. Evaporator
CORRECT ANSWER: D
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EXPERT RATIONALE: The evaporator boils low-pressure liquid refrigerant, absorbing
heat from the air or water in the conditioned space.
QUESTION 5
What refrigerant oil type is typically used with R-410A systems?
A. Mineral oil
B. Alkylbenzene
C. Polyol ester (POE)
D. PAG oil
CORRECT ANSWER: C
EXPERT RATIONALE: R-410A uses polyol ester (POE) oil because mineral oil is not
miscible with HFC refrigerants.
QUESTION 6
Under EPA Section 608, the required evacuation level for a small appliance with 5 lbs of
refrigerant before opening to the atmosphere for major repair using recovery
equipment manufactured before November 15, 1993 is:
A. 0 psig
B. 4 inches of mercury vacuum
C. 10 inches of mercury vacuum
D. 15 inches of mercury vacuum
CORRECT ANSWER: B
EXPERT RATIONALE: For small appliances with recovery equipment built before
11/15/1993, the required recovery vacuum is 4 inches Hg.
QUESTION 7
The primary function of a filter-drier in a refrigeration system is to:
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A. Remove moisture and particulates
B. Increase subcooling
C. Store excess refrigerant
D. Reduce compressor noise
CORRECT ANSWER: A
EXPERT RATIONALE: Filter-driers combine desiccant and filter media to trap moisture,
acids, and solid contaminants, protecting the compressor and metering device.
QUESTION 8
What is the minimum diameter vent connector for a Category I gas appliance with an
input rating of 80,000 BTU/h, per IFGC?
A. 2 inches
B. 3 inches
C. 4 inches
D. 5 inches
CORRECT ANSWER: B
EXPERT RATIONALE: IFGC vent sizing tables generally require a 3-inch connector for
80,000 BTU/h natural draft appliances with typical vent height.
QUESTION 9
In psychrometrics, the dew point temperature is the temperature at which:
A. Air reaches 100% relative humidity and condensation begins
B. Wet-bulb equals dry-bulb
C. Sensible heat equals latent heat
D. Enthalpy is zero
CORRECT ANSWER: A
Texas (TX) Class B Air Conditioning and Refrigeration
Contractor Exam | Latest Verified Questions and Detailed
Answers
OVERVIEW DESCRIPTION
This Comprehensive set of multiple choice questions is designed for the Texas Class B
Air Conditioning and Refrigeration Contractor Exam, an open-book licensing test
administered by PSI. The exam evaluates technical knowledge and code compliance for
residential and light commercial HVAC/R systems with a cooling capacity up to 25 tons
or heating up to 1.5 million BTU/h. The content spans HVAC systems design (Manual J,
N, and D), refrigeration principles and components, refrigerant handling and EPA
regulations, ductwork, piping and venting, electrical and gas codes, installation and
maintenance practices, as well as business law and Texas licensing rules.
QUESTION 1
According to Manual J, what is the primary purpose of the design temperature
difference (DTD)?
A. To size ductwork
B. To calculate heat loss and gain through building envelope components
C. To determine refrigerant charge
D. To select grille sizes
CORRECT ANSWER: B
EXPERT RATIONALE: Manual J uses DTD (indoor–outdoor temperature difference) to
compute conduction heat gains/losses through walls, ceilings, and floors.
QUESTION 2
A Class B license in Texas authorizes work on air conditioning systems with a maximum
cooling capacity of:
A. 15 tons
,2|Page
B. 25 tons
C. 50 tons
D. 100 tons
CORRECT ANSWER: B
EXPERT RATIONALE: The Class B endorsement is limited to 25 tons cooling and 1.5
million BTU/h heating capacity.
QUESTION 3
Manual N is used primarily for:
A. Residential heat loss calculations
B. Small commercial load calculations
C. Duct sizing for single-family homes
D. Refrigerant piping design
CORRECT ANSWER: B
EXPERT RATIONALE: Manual N provides procedures for heating and cooling load
calculations in light commercial buildings, complementing Manual J for residential.
QUESTION 4
In the basic vapor-compression refrigeration cycle, the component that absorbs heat
from the conditioned space is the:
A. Compressor
B. Condenser
C. Expansion valve
D. Evaporator
CORRECT ANSWER: D
,3|Page
EXPERT RATIONALE: The evaporator boils low-pressure liquid refrigerant, absorbing
heat from the air or water in the conditioned space.
QUESTION 5
What refrigerant oil type is typically used with R-410A systems?
A. Mineral oil
B. Alkylbenzene
C. Polyol ester (POE)
D. PAG oil
CORRECT ANSWER: C
EXPERT RATIONALE: R-410A uses polyol ester (POE) oil because mineral oil is not
miscible with HFC refrigerants.
QUESTION 6
Under EPA Section 608, the required evacuation level for a small appliance with 5 lbs of
refrigerant before opening to the atmosphere for major repair using recovery
equipment manufactured before November 15, 1993 is:
A. 0 psig
B. 4 inches of mercury vacuum
C. 10 inches of mercury vacuum
D. 15 inches of mercury vacuum
CORRECT ANSWER: B
EXPERT RATIONALE: For small appliances with recovery equipment built before
11/15/1993, the required recovery vacuum is 4 inches Hg.
QUESTION 7
The primary function of a filter-drier in a refrigeration system is to:
, 4|Page
A. Remove moisture and particulates
B. Increase subcooling
C. Store excess refrigerant
D. Reduce compressor noise
CORRECT ANSWER: A
EXPERT RATIONALE: Filter-driers combine desiccant and filter media to trap moisture,
acids, and solid contaminants, protecting the compressor and metering device.
QUESTION 8
What is the minimum diameter vent connector for a Category I gas appliance with an
input rating of 80,000 BTU/h, per IFGC?
A. 2 inches
B. 3 inches
C. 4 inches
D. 5 inches
CORRECT ANSWER: B
EXPERT RATIONALE: IFGC vent sizing tables generally require a 3-inch connector for
80,000 BTU/h natural draft appliances with typical vent height.
QUESTION 9
In psychrometrics, the dew point temperature is the temperature at which:
A. Air reaches 100% relative humidity and condensation begins
B. Wet-bulb equals dry-bulb
C. Sensible heat equals latent heat
D. Enthalpy is zero
CORRECT ANSWER: A
