TEXAS HVAC CERTIFICATION EXAM
230 Practice MCQs with Answers & Rationales
SECTION 1: FUNDAMENTALS OF HVAC &
THERMODYNAMICS
1. What does HVAC stand for?
A) Heating, Ventilation, and Air Conditioning B) Heat, Vapor, Air, and Cooling C) Heating,
Venting, Airflow, and Compression D) High Voltage Air Conditioning
(Correct answer: A) Rationale: HVAC stands for Heating, Ventilation, and Air Conditioning.
It refers to the technology and systems used to provide thermal comfort and acceptable indoor air
quality in residential, commercial, and industrial buildings.
2. Which law of thermodynamics states that heat flows naturally from a warmer object to a
cooler object?
A) First Law of Thermodynamics B) Second Law of Thermodynamics C) Third Law of
Thermodynamics D) Zeroth Law of Thermodynamics
(Correct answer: B) Rationale: The Second Law of Thermodynamics states that heat naturally
flows from a region of higher temperature to a region of lower temperature. Refrigeration and air
conditioning work against this natural flow, requiring energy input to move heat from a cool
space to a warmer environment.
3. What is "sensible heat"?
A) Heat that causes a change in temperature without a change in state B) Heat that causes a
change in state without a change in temperature C) The total heat content of air D) Heat
measured in British Thermal Units per hour
(Correct answer: A) Rationale: Sensible heat is heat that can be "sensed" or measured by a
thermometer because it causes a change in temperature. It does not involve a change in the
physical state of the substance (e.g., liquid to gas).
,4. What is "latent heat"?
A) Heat that causes a change in temperature B) Heat that causes a change in state (e.g., liquid to
vapor) without a change in temperature C) The heat stored in a refrigerant D) Heat measured by
a psychrometric chart
(Correct answer: B) Rationale: Latent heat is heat absorbed or released during a change of
state (phase change) — such as liquid to vapor (latent heat of vaporization) or liquid to solid
(latent heat of fusion) — without any change in temperature. Air conditioning removes both
sensible and latent heat from a space.
5. One British Thermal Unit (BTU) is defined as the amount of heat required to:
A) Raise 1 pound of water by 10°F B) Raise 1 pound of water by 1°F C) Raise 1 gallon of water
by 1°F D) Melt 1 pound of ice
(Correct answer: B) Rationale: One BTU (British Thermal Unit) is the amount of heat energy
required to raise the temperature of one pound of water by one degree Fahrenheit. It is the
standard unit of heat measurement used in HVAC calculations in the United States.
6. What is the relationship between temperature and pressure for a refrigerant in a closed system?
A) As pressure increases, temperature decreases B) Temperature and pressure are unrelated in a
closed system C) As pressure increases, the saturation temperature (boiling point) of the
refrigerant increases D) Temperature and pressure are only related during the compression stage
(Correct answer: C) Rationale: For refrigerants, pressure and saturation temperature are
directly related — as pressure increases, the boiling/condensing temperature increases. This
pressure-temperature (P-T) relationship is fundamental to how refrigeration cycles work and is
essential for HVAC diagnostics.
7. What is the "specific heat" of a substance?
A) The amount of heat required to change the state of 1 pound of a substance B) The amount of
heat required to raise 1 pound of a substance by 1°F C) The temperature at which a substance
changes state D) The total heat content of a substance
,(Correct answer: B) Rationale: Specific heat is the amount of heat (in BTUs) required to raise
the temperature of one pound of a substance by one degree Fahrenheit. Water has a specific heat
of 1.0 BTU/lb·°F, which is relatively high, making it an effective heat transfer medium.
8. In the refrigeration cycle, at which component does the refrigerant absorb heat from the
conditioned space?
A) Condenser B) Compressor C) Evaporator D) Metering device
(Correct answer: C) Rationale: The evaporator is where the refrigerant absorbs heat from the
conditioned space (indoor air). The refrigerant evaporates (changes from liquid to vapor) by
absorbing latent and sensible heat from the air passing over the evaporator coil, cooling the air.
9. In the refrigeration cycle, at which component does the refrigerant release heat to the outside
environment?
A) Evaporator B) Compressor C) Expansion valve D) Condenser
(Correct answer: D) Rationale: The condenser is where the refrigerant rejects (releases) heat to
the outside environment. The high-pressure, high-temperature refrigerant vapor condenses back
into liquid by releasing heat to the outdoor air (or water in water-cooled systems).
10. What is the purpose of the compressor in a refrigeration system?
A) To cool the refrigerant by reducing its pressure B) To increase the pressure and temperature
of the refrigerant vapor, enabling it to release heat at the condenser C) To meter the flow of
refrigerant into the evaporator D) To filter contaminants from the refrigerant
(Correct answer: B) Rationale: The compressor is the "heart" of the refrigeration system. It
compresses low-pressure refrigerant vapor from the evaporator into high-pressure, high-
temperature vapor, which can then release heat at the condenser. It is driven by an electric motor
and is where energy is added to the refrigeration cycle.
SECTION 2: REFRIGERANTS & EPA REGULATIONS
11. Under EPA Section 608 of the Clean Air Act, technicians who service refrigeration and air
conditioning equipment must be:
, A) Licensed by their state only B) EPA Section 608 certified in the appropriate type C) Certified
by the manufacturer of the equipment D) Certified only if handling more than 50 pounds of
refrigerant
(Correct answer: B) Rationale: EPA Section 608 of the Clean Air Act requires all technicians
who maintain, service, repair, or dispose of appliances containing regulated refrigerants to be
certified. This regulation is enforced by the EPA to prevent the venting of ozone-depleting and
greenhouse gas refrigerants.
12. Which refrigerant was widely used in residential air conditioning but was phased out due to
its ozone-depleting potential?
A) R-410A B) R-22 (Freon) C) R-134a D) R-32
(Correct answer: B) Rationale: R-22 (chlorodifluoromethane, also known as Freon) was the
standard refrigerant for residential air conditioning for decades. It was phased out under the
Montreal Protocol due to its significant ozone-depleting potential (ODP). Its production and
import were banned in the US as of January 1, 2020.
13. What refrigerant replaced R-22 as the standard for new residential air conditioning systems
in the United States?
A) R-12 B) R-134a C) R-410A D) R-502
(Correct answer: C) Rationale: R-410A (a hydrofluorocarbon/HFC blend) replaced R-22 in
new residential air conditioning equipment. It has zero ozone depletion potential (ODP), though
it has a high global warming potential (GWP). It operates at significantly higher pressures than
R-22.
14. Under EPA Section 608, it is illegal to:
A) Recover refrigerant before servicing equipment B) Knowingly vent refrigerants into the
atmosphere C) Use reclaimed refrigerant in the same type of equipment D) Charge a customer
for refrigerant recovery
(Correct answer: B) Rationale: EPA Section 608 prohibits the knowing venting of Class I and
Class II refrigerants (including HCFCs and HFCs) into the atmosphere. Technicians must
recover refrigerant using EPA-approved recovery equipment before opening a system for service
or disposal.
230 Practice MCQs with Answers & Rationales
SECTION 1: FUNDAMENTALS OF HVAC &
THERMODYNAMICS
1. What does HVAC stand for?
A) Heating, Ventilation, and Air Conditioning B) Heat, Vapor, Air, and Cooling C) Heating,
Venting, Airflow, and Compression D) High Voltage Air Conditioning
(Correct answer: A) Rationale: HVAC stands for Heating, Ventilation, and Air Conditioning.
It refers to the technology and systems used to provide thermal comfort and acceptable indoor air
quality in residential, commercial, and industrial buildings.
2. Which law of thermodynamics states that heat flows naturally from a warmer object to a
cooler object?
A) First Law of Thermodynamics B) Second Law of Thermodynamics C) Third Law of
Thermodynamics D) Zeroth Law of Thermodynamics
(Correct answer: B) Rationale: The Second Law of Thermodynamics states that heat naturally
flows from a region of higher temperature to a region of lower temperature. Refrigeration and air
conditioning work against this natural flow, requiring energy input to move heat from a cool
space to a warmer environment.
3. What is "sensible heat"?
A) Heat that causes a change in temperature without a change in state B) Heat that causes a
change in state without a change in temperature C) The total heat content of air D) Heat
measured in British Thermal Units per hour
(Correct answer: A) Rationale: Sensible heat is heat that can be "sensed" or measured by a
thermometer because it causes a change in temperature. It does not involve a change in the
physical state of the substance (e.g., liquid to gas).
,4. What is "latent heat"?
A) Heat that causes a change in temperature B) Heat that causes a change in state (e.g., liquid to
vapor) without a change in temperature C) The heat stored in a refrigerant D) Heat measured by
a psychrometric chart
(Correct answer: B) Rationale: Latent heat is heat absorbed or released during a change of
state (phase change) — such as liquid to vapor (latent heat of vaporization) or liquid to solid
(latent heat of fusion) — without any change in temperature. Air conditioning removes both
sensible and latent heat from a space.
5. One British Thermal Unit (BTU) is defined as the amount of heat required to:
A) Raise 1 pound of water by 10°F B) Raise 1 pound of water by 1°F C) Raise 1 gallon of water
by 1°F D) Melt 1 pound of ice
(Correct answer: B) Rationale: One BTU (British Thermal Unit) is the amount of heat energy
required to raise the temperature of one pound of water by one degree Fahrenheit. It is the
standard unit of heat measurement used in HVAC calculations in the United States.
6. What is the relationship between temperature and pressure for a refrigerant in a closed system?
A) As pressure increases, temperature decreases B) Temperature and pressure are unrelated in a
closed system C) As pressure increases, the saturation temperature (boiling point) of the
refrigerant increases D) Temperature and pressure are only related during the compression stage
(Correct answer: C) Rationale: For refrigerants, pressure and saturation temperature are
directly related — as pressure increases, the boiling/condensing temperature increases. This
pressure-temperature (P-T) relationship is fundamental to how refrigeration cycles work and is
essential for HVAC diagnostics.
7. What is the "specific heat" of a substance?
A) The amount of heat required to change the state of 1 pound of a substance B) The amount of
heat required to raise 1 pound of a substance by 1°F C) The temperature at which a substance
changes state D) The total heat content of a substance
,(Correct answer: B) Rationale: Specific heat is the amount of heat (in BTUs) required to raise
the temperature of one pound of a substance by one degree Fahrenheit. Water has a specific heat
of 1.0 BTU/lb·°F, which is relatively high, making it an effective heat transfer medium.
8. In the refrigeration cycle, at which component does the refrigerant absorb heat from the
conditioned space?
A) Condenser B) Compressor C) Evaporator D) Metering device
(Correct answer: C) Rationale: The evaporator is where the refrigerant absorbs heat from the
conditioned space (indoor air). The refrigerant evaporates (changes from liquid to vapor) by
absorbing latent and sensible heat from the air passing over the evaporator coil, cooling the air.
9. In the refrigeration cycle, at which component does the refrigerant release heat to the outside
environment?
A) Evaporator B) Compressor C) Expansion valve D) Condenser
(Correct answer: D) Rationale: The condenser is where the refrigerant rejects (releases) heat to
the outside environment. The high-pressure, high-temperature refrigerant vapor condenses back
into liquid by releasing heat to the outdoor air (or water in water-cooled systems).
10. What is the purpose of the compressor in a refrigeration system?
A) To cool the refrigerant by reducing its pressure B) To increase the pressure and temperature
of the refrigerant vapor, enabling it to release heat at the condenser C) To meter the flow of
refrigerant into the evaporator D) To filter contaminants from the refrigerant
(Correct answer: B) Rationale: The compressor is the "heart" of the refrigeration system. It
compresses low-pressure refrigerant vapor from the evaporator into high-pressure, high-
temperature vapor, which can then release heat at the condenser. It is driven by an electric motor
and is where energy is added to the refrigeration cycle.
SECTION 2: REFRIGERANTS & EPA REGULATIONS
11. Under EPA Section 608 of the Clean Air Act, technicians who service refrigeration and air
conditioning equipment must be:
, A) Licensed by their state only B) EPA Section 608 certified in the appropriate type C) Certified
by the manufacturer of the equipment D) Certified only if handling more than 50 pounds of
refrigerant
(Correct answer: B) Rationale: EPA Section 608 of the Clean Air Act requires all technicians
who maintain, service, repair, or dispose of appliances containing regulated refrigerants to be
certified. This regulation is enforced by the EPA to prevent the venting of ozone-depleting and
greenhouse gas refrigerants.
12. Which refrigerant was widely used in residential air conditioning but was phased out due to
its ozone-depleting potential?
A) R-410A B) R-22 (Freon) C) R-134a D) R-32
(Correct answer: B) Rationale: R-22 (chlorodifluoromethane, also known as Freon) was the
standard refrigerant for residential air conditioning for decades. It was phased out under the
Montreal Protocol due to its significant ozone-depleting potential (ODP). Its production and
import were banned in the US as of January 1, 2020.
13. What refrigerant replaced R-22 as the standard for new residential air conditioning systems
in the United States?
A) R-12 B) R-134a C) R-410A D) R-502
(Correct answer: C) Rationale: R-410A (a hydrofluorocarbon/HFC blend) replaced R-22 in
new residential air conditioning equipment. It has zero ozone depletion potential (ODP), though
it has a high global warming potential (GWP). It operates at significantly higher pressures than
R-22.
14. Under EPA Section 608, it is illegal to:
A) Recover refrigerant before servicing equipment B) Knowingly vent refrigerants into the
atmosphere C) Use reclaimed refrigerant in the same type of equipment D) Charge a customer
for refrigerant recovery
(Correct answer: B) Rationale: EPA Section 608 prohibits the knowing venting of Class I and
Class II refrigerants (including HCFCs and HFCs) into the atmosphere. Technicians must
recover refrigerant using EPA-approved recovery equipment before opening a system for service
or disposal.
