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TDLR Texas (TX) Class A Air Conditioning and Refrigeration
Contractor License Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION
This comprehensive set of multiple-choice questions is designed for the Texas Class A
Air Conditioning and Refrigeration Contractor License Exam, an open-book
assessment administered by the Texas Department of Licensing and Regulation
(TDLR). It evaluates high-level commercial design, troubleshooting, and regulatory
knowledge, covering HVACR systems and design, load calculations, the International
Mechanical, Fuel Gas, and Uniform Mechanical Codes, electrical and mechanical
systems, safety requirements, and Texas laws and rules governing contractor
operations.
QUESTION 1
In a vapor-compression refrigeration cycle, the component that increases the pressure
of the refrigerant vapor is the:
A) Evaporator
B) Condenser
C) Compressor
D) Expansion valve
CORRECT ANSWER: C
EXPERT RATIONALE: The compressor raises the pressure and temperature of the
refrigerant vapor so it can condense at a higher temperature.
QUESTION 2
Which refrigerant is classified as an HFC, has a global warming potential (GWP) of 1430,
and is frequently used in centrifugal chillers and automotive air conditioning?
A) R-22
B) R-410A
C) R-134a
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D) R-404A
CORRECT ANSWER: C
EXPERT RATIONALE: R-134a is a pure HFC with GWP 1430, suitable for medium-pressure
chillers and mobile AC.
QUESTION 3
In a basic refrigeration cycle, the component where the refrigerant absorbs heat from
the conditioned space is the:
A) Compressor
B) Condenser
C) Evaporator
D) Receiver
CORRECT ANSWER: C
EXPERT RATIONALE: The evaporator allows liquid refrigerant to boil, absorbing heat
from the surrounding air or water.
QUESTION 4
The state of refrigerant entering the compressor should be:
A) Subcooled liquid
B) Saturated liquid
C) Superheated vapor
D) Saturated vapor
CORRECT ANSWER: C
EXPERT RATIONALE: To prevent liquid slugging, the refrigerant must enter the
compressor as superheated vapor.
QUESTION 5
The term “subcooling” refers to:
A) Cooling the vapor below its saturation temperature
B) Cooling the liquid refrigerant below its saturation temperature
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C) Heating the liquid above saturation
D) Reducing pressure below vapor pressure
CORRECT ANSWER: B
EXPERT RATIONALE: Subcooling is cooling the liquid refrigerant below its condensing
temperature to ensure a solid column of liquid at the expansion device.
QUESTION 6
An evaporator superheat of 10°F means the suction line temperature is:
A) 10°F below evaporator saturation temperature
B) 10°F above evaporator saturation temperature
C) 10°F above condensing temperature
D) Equal to the evaporator saturation temperature
CORRECT ANSWER: B
EXPERT RATIONALE: Superheat is the temperature rise of the refrigerant vapor above its
saturation point at the evaporator outlet.
QUESTION 7
Which of the following is a zeotropic refrigerant blend with a significant temperature
glide?
A) R-22
B) R-410A
C) R-407C
D) R-134a
CORRECT ANSWER: C
EXPERT RATIONALE: R-407C is a zeotropic blend with up to 10°F glide; it must be
charged as a liquid to avoid fractionation.
QUESTION 8
The function of the metering device in a refrigeration system is to:
A) Increase refrigerant pressure
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B) Regulate refrigerant flow and create a pressure drop
C) Compress the vapor
D) Remove moisture from the refrigerant
CORRECT ANSWER: B
EXPERT RATIONALE: The metering device (TXV, capillary tube, etc.) reduces liquid
pressure, causing flash gas and controlling flow into the evaporator.
QUESTION 9
In a water-cooled condenser, the condensing temperature is typically maintained by
controlling:
A) Compressor speed
B) Cooling tower fan or water flow
C) Evaporator pressure
D) The subcooling circuit
CORRECT ANSWER: B
EXPERT RATIONALE: Modulating water flow or tower fan adjusts heat rejection to
maintain the desired head pressure.
QUESTION 10
The Net Refrigeration Effect (NRE) is defined as the:
A) Total heat rejected by the condenser
B) Enthalpy difference between evaporator outlet and inlet
C) Heat of compression
D) Condenser subcooling amount
CORRECT ANSWER: B
EXPERT RATIONALE: NRE is the useful cooling per pound of refrigerant, calculated as the
enthalpy difference across the evaporator.
QUESTION 11
Which compressor type uses an orbiting scroll and a fixed scroll to compress gas?
TDLR Texas (TX) Class A Air Conditioning and Refrigeration
Contractor License Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION
This comprehensive set of multiple-choice questions is designed for the Texas Class A
Air Conditioning and Refrigeration Contractor License Exam, an open-book
assessment administered by the Texas Department of Licensing and Regulation
(TDLR). It evaluates high-level commercial design, troubleshooting, and regulatory
knowledge, covering HVACR systems and design, load calculations, the International
Mechanical, Fuel Gas, and Uniform Mechanical Codes, electrical and mechanical
systems, safety requirements, and Texas laws and rules governing contractor
operations.
QUESTION 1
In a vapor-compression refrigeration cycle, the component that increases the pressure
of the refrigerant vapor is the:
A) Evaporator
B) Condenser
C) Compressor
D) Expansion valve
CORRECT ANSWER: C
EXPERT RATIONALE: The compressor raises the pressure and temperature of the
refrigerant vapor so it can condense at a higher temperature.
QUESTION 2
Which refrigerant is classified as an HFC, has a global warming potential (GWP) of 1430,
and is frequently used in centrifugal chillers and automotive air conditioning?
A) R-22
B) R-410A
C) R-134a
,2|Page
D) R-404A
CORRECT ANSWER: C
EXPERT RATIONALE: R-134a is a pure HFC with GWP 1430, suitable for medium-pressure
chillers and mobile AC.
QUESTION 3
In a basic refrigeration cycle, the component where the refrigerant absorbs heat from
the conditioned space is the:
A) Compressor
B) Condenser
C) Evaporator
D) Receiver
CORRECT ANSWER: C
EXPERT RATIONALE: The evaporator allows liquid refrigerant to boil, absorbing heat
from the surrounding air or water.
QUESTION 4
The state of refrigerant entering the compressor should be:
A) Subcooled liquid
B) Saturated liquid
C) Superheated vapor
D) Saturated vapor
CORRECT ANSWER: C
EXPERT RATIONALE: To prevent liquid slugging, the refrigerant must enter the
compressor as superheated vapor.
QUESTION 5
The term “subcooling” refers to:
A) Cooling the vapor below its saturation temperature
B) Cooling the liquid refrigerant below its saturation temperature
,3|Page
C) Heating the liquid above saturation
D) Reducing pressure below vapor pressure
CORRECT ANSWER: B
EXPERT RATIONALE: Subcooling is cooling the liquid refrigerant below its condensing
temperature to ensure a solid column of liquid at the expansion device.
QUESTION 6
An evaporator superheat of 10°F means the suction line temperature is:
A) 10°F below evaporator saturation temperature
B) 10°F above evaporator saturation temperature
C) 10°F above condensing temperature
D) Equal to the evaporator saturation temperature
CORRECT ANSWER: B
EXPERT RATIONALE: Superheat is the temperature rise of the refrigerant vapor above its
saturation point at the evaporator outlet.
QUESTION 7
Which of the following is a zeotropic refrigerant blend with a significant temperature
glide?
A) R-22
B) R-410A
C) R-407C
D) R-134a
CORRECT ANSWER: C
EXPERT RATIONALE: R-407C is a zeotropic blend with up to 10°F glide; it must be
charged as a liquid to avoid fractionation.
QUESTION 8
The function of the metering device in a refrigeration system is to:
A) Increase refrigerant pressure
, 4|Page
B) Regulate refrigerant flow and create a pressure drop
C) Compress the vapor
D) Remove moisture from the refrigerant
CORRECT ANSWER: B
EXPERT RATIONALE: The metering device (TXV, capillary tube, etc.) reduces liquid
pressure, causing flash gas and controlling flow into the evaporator.
QUESTION 9
In a water-cooled condenser, the condensing temperature is typically maintained by
controlling:
A) Compressor speed
B) Cooling tower fan or water flow
C) Evaporator pressure
D) The subcooling circuit
CORRECT ANSWER: B
EXPERT RATIONALE: Modulating water flow or tower fan adjusts heat rejection to
maintain the desired head pressure.
QUESTION 10
The Net Refrigeration Effect (NRE) is defined as the:
A) Total heat rejected by the condenser
B) Enthalpy difference between evaporator outlet and inlet
C) Heat of compression
D) Condenser subcooling amount
CORRECT ANSWER: B
EXPERT RATIONALE: NRE is the useful cooling per pound of refrigerant, calculated as the
enthalpy difference across the evaporator.
QUESTION 11
Which compressor type uses an orbiting scroll and a fixed scroll to compress gas?
