NATE A/C EXAM #1
50+ (Fully Updated 2026) Exam Questions + Verified & Rationalized
Answers | A+ Graded
100% Guarantee Pass
📋 DOCUMENT OVERVIEW 50 Qs
This document, "NATE A/C Exam #1", covers specific topics related to air conditioning, including
evaporator and condenser operation, refrigerant recovery and handling, metering devices, system
pressure and temperature, and cooling tower principles. It provides 50 questions with correct answers,
along with detailed explanations and rationales, as well as diagrams and images to aid understanding.
Students can utilize this document to study, review, and gain a deeper understanding of air conditioning
concepts, ultimately enhancing their preparation for exams and certifications.
✓ Verified Answers ✓ Exam Ready ✓ Study Guide
Trusted by thousands of students and professionals worldwide
EXAM QUESTIONS
QUESTION 1
Low airflow over a residential split system air conditioning evaporator can cause
A: Liquid flood-back to the compressor
B: A decrease in compression ratio
C: An increase in suction line superheat
D: Oil logging in the evaporator
CORRECT ANSWER
A: Liquid flood-back to the compressor
RATIONALE: Low airflow over the evaporator can cause a buildup of liquid refrigerant in the evaporator coils, which can
then be sucked back into the compressor, potentially causing damage. This is known as "flood-back," and it occurs
because the reduced airflow prevents the proper evaporation of the refrigerant, allowing it to accumulate in a liquid
state.
QUESTION 2
Which of the following is the correct sequence of work?
A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the
system.
B: Recover refrigerant, evacuate the system, replace filter core, recharge the system.
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, C: Attach gauge manifold, evacuate the system, replace filter core, recover refrigerant, recharge the
system.
D: Attach gauge manifold, recharge the system, evacuate the system, replace filter core.
CORRECT ANSWER
A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the
system.
RATIONALE: The correct sequence involves attaching a gauge manifold to monitor system pressures, which is essential
for a safe and controlled process of refrigerant recovery, evacuation, replacement of the filter core, and recharging. This
sequence ensures that the system is properly prepared and maintained throughout the process, preventing damage and
ensuring efficiency.
QUESTION 3
As the pressure on a liquid is increased, the vaporization temperature of the liquid
A: Decreases
B: Increases
C: Remains unchanged
D: Varies
CORRECT ANSWER
B: Increases
RATIONALE: When pressure is increased on a liquid, the molecules are forced closer together, requiring more energy to
overcome the stronger intermolecular forces and transition into the gas phase, thus increasing the vaporization
temperature. This relationship is described by the principle that increasing pressure raises the boiling point of a
substance, as the energy required for vaporization increases.
QUESTION 4
An oil separator must be mounted
A: Level
B: Below the compressor crankcase
C: Above the compressor crankcase
D: In the suction line
CORRECT ANSWER
A: Level
RATIONALE: An oil separator must be mounted level to ensure that oil droplets in the gas stream settle properly,
allowing for efficient separation and minimizing the risk of clogged lines or damaged equipment. This is because gravity
plays a crucial role in the oil separation process, and a tilted separator would disrupt the natural flow of liquid droplets,
reducing its effectiveness.
QUESTION 5
Which of the following metering devices controls evaporator pressure?
A: Thermostatic expansion valve
B: Fixed orifice
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, C: Low side float
D: None of these
CORRECT ANSWER
D: None of these
An automatic expansion valve controls evaporator pressure.
RATIONALE: An automatic expansion valve is designed to regulate the flow of refrigerant into the evaporator, which in
turn controls the evaporator pressure by modulating the amount of refrigerant entering the system. This ability to adjust
refrigerant flow makes it the correct answer, as it directly impacts the evaporator pressure and is a metering device that
controls it.
QUESTION 6
The purpose of the external equalizer on a thermostatic expansion valve is
A: To equalize evaporator pressure drop with respect to the TEV
B: To equalize the evaporator pressure drop
C: To help prevent liquid floodback
D: To allow the high side pressure to equalize to the low side when the compressor cycles off
CORRECT ANSWER
A: To equalize evaporator pressure drop with respect to the TEV
RATIONALE: The external equalizer on a thermostatic expansion valve (TEV) is necessary to maintain a consistent
pressure drop across the valve, ensuring proper operation and preventing potential issues such as over- or under-
expansion of the refrigerant. By equalizing evaporator pressure drop with respect to the TEV, the external equalizer helps
to maintain a stable refrigerant flow and prevents damage to the system components.
QUESTION 7
The higher the MERV rating of a filter-drier, the
A: More efficient the drier at absorbing moisture
B: Less efficient the drier at absorbing moisture
C: Smaller the particles the filter can entrap
D: MERV does not apply to filter-driers
CORRECT ANSWER
D: MERV does not apply to filter-driers
Minimum Efficiency Reporting Value - MERV ratings are used to rate the ability of an air conditioning filter
to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall
efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass
through the filter. Filters with a merv rating of 9 to 12 are used in commercial and industrial applications
and will stop particles in the 1 to 3 micron range. These filters are a great choice for home owners who
want the best dust control possible. When using filters with Merv 9 ratings and above it is important to
clean or replace them when recommended by the manufacturer because they will have a negative effect
on air flow when they become dirty. This can lead to performance problems and decreased operating
efficiency. The most efficient filters have merv ratings of 13 to 16 and will stop particles as small as .3
microns. These filters are used in hospitals and other super clean environments.
Trusted by thousands of students and professionals worldwide
Page 3 of 18
50+ (Fully Updated 2026) Exam Questions + Verified & Rationalized
Answers | A+ Graded
100% Guarantee Pass
📋 DOCUMENT OVERVIEW 50 Qs
This document, "NATE A/C Exam #1", covers specific topics related to air conditioning, including
evaporator and condenser operation, refrigerant recovery and handling, metering devices, system
pressure and temperature, and cooling tower principles. It provides 50 questions with correct answers,
along with detailed explanations and rationales, as well as diagrams and images to aid understanding.
Students can utilize this document to study, review, and gain a deeper understanding of air conditioning
concepts, ultimately enhancing their preparation for exams and certifications.
✓ Verified Answers ✓ Exam Ready ✓ Study Guide
Trusted by thousands of students and professionals worldwide
EXAM QUESTIONS
QUESTION 1
Low airflow over a residential split system air conditioning evaporator can cause
A: Liquid flood-back to the compressor
B: A decrease in compression ratio
C: An increase in suction line superheat
D: Oil logging in the evaporator
CORRECT ANSWER
A: Liquid flood-back to the compressor
RATIONALE: Low airflow over the evaporator can cause a buildup of liquid refrigerant in the evaporator coils, which can
then be sucked back into the compressor, potentially causing damage. This is known as "flood-back," and it occurs
because the reduced airflow prevents the proper evaporation of the refrigerant, allowing it to accumulate in a liquid
state.
QUESTION 2
Which of the following is the correct sequence of work?
A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the
system.
B: Recover refrigerant, evacuate the system, replace filter core, recharge the system.
Trusted by thousands of students and professionals worldwide Page 1 of 18
, C: Attach gauge manifold, evacuate the system, replace filter core, recover refrigerant, recharge the
system.
D: Attach gauge manifold, recharge the system, evacuate the system, replace filter core.
CORRECT ANSWER
A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the
system.
RATIONALE: The correct sequence involves attaching a gauge manifold to monitor system pressures, which is essential
for a safe and controlled process of refrigerant recovery, evacuation, replacement of the filter core, and recharging. This
sequence ensures that the system is properly prepared and maintained throughout the process, preventing damage and
ensuring efficiency.
QUESTION 3
As the pressure on a liquid is increased, the vaporization temperature of the liquid
A: Decreases
B: Increases
C: Remains unchanged
D: Varies
CORRECT ANSWER
B: Increases
RATIONALE: When pressure is increased on a liquid, the molecules are forced closer together, requiring more energy to
overcome the stronger intermolecular forces and transition into the gas phase, thus increasing the vaporization
temperature. This relationship is described by the principle that increasing pressure raises the boiling point of a
substance, as the energy required for vaporization increases.
QUESTION 4
An oil separator must be mounted
A: Level
B: Below the compressor crankcase
C: Above the compressor crankcase
D: In the suction line
CORRECT ANSWER
A: Level
RATIONALE: An oil separator must be mounted level to ensure that oil droplets in the gas stream settle properly,
allowing for efficient separation and minimizing the risk of clogged lines or damaged equipment. This is because gravity
plays a crucial role in the oil separation process, and a tilted separator would disrupt the natural flow of liquid droplets,
reducing its effectiveness.
QUESTION 5
Which of the following metering devices controls evaporator pressure?
A: Thermostatic expansion valve
B: Fixed orifice
Trusted by thousands of students and professionals worldwide Page 2 of 18
, C: Low side float
D: None of these
CORRECT ANSWER
D: None of these
An automatic expansion valve controls evaporator pressure.
RATIONALE: An automatic expansion valve is designed to regulate the flow of refrigerant into the evaporator, which in
turn controls the evaporator pressure by modulating the amount of refrigerant entering the system. This ability to adjust
refrigerant flow makes it the correct answer, as it directly impacts the evaporator pressure and is a metering device that
controls it.
QUESTION 6
The purpose of the external equalizer on a thermostatic expansion valve is
A: To equalize evaporator pressure drop with respect to the TEV
B: To equalize the evaporator pressure drop
C: To help prevent liquid floodback
D: To allow the high side pressure to equalize to the low side when the compressor cycles off
CORRECT ANSWER
A: To equalize evaporator pressure drop with respect to the TEV
RATIONALE: The external equalizer on a thermostatic expansion valve (TEV) is necessary to maintain a consistent
pressure drop across the valve, ensuring proper operation and preventing potential issues such as over- or under-
expansion of the refrigerant. By equalizing evaporator pressure drop with respect to the TEV, the external equalizer helps
to maintain a stable refrigerant flow and prevents damage to the system components.
QUESTION 7
The higher the MERV rating of a filter-drier, the
A: More efficient the drier at absorbing moisture
B: Less efficient the drier at absorbing moisture
C: Smaller the particles the filter can entrap
D: MERV does not apply to filter-driers
CORRECT ANSWER
D: MERV does not apply to filter-driers
Minimum Efficiency Reporting Value - MERV ratings are used to rate the ability of an air conditioning filter
to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall
efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass
through the filter. Filters with a merv rating of 9 to 12 are used in commercial and industrial applications
and will stop particles in the 1 to 3 micron range. These filters are a great choice for home owners who
want the best dust control possible. When using filters with Merv 9 ratings and above it is important to
clean or replace them when recommended by the manufacturer because they will have a negative effect
on air flow when they become dirty. This can lead to performance problems and decreased operating
efficiency. The most efficient filters have merv ratings of 13 to 16 and will stop particles as small as .3
microns. These filters are used in hospitals and other super clean environments.
Trusted by thousands of students and professionals worldwide
Page 3 of 18
