Indiana Hvac Contractor Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
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1. A technician measures a refrigerant system with low suction pressure and
high superheat. What is the most likely cause?
A. Overcharged system
B. Undercharged system
C. Dirty condenser coil
D. Faulty reversing valve
Answer: B
A low suction pressure combined with high superheat typically indicates that the
evaporator is being starved of refrigerant, which is a classic symptom of an
undercharged system. With insufficient refrigerant mass flow, the evaporator
cannot maintain proper saturation, leading to excessive temperature rise in the
suction line. While a dirty condenser can raise head pressure, it does not usually
produce high superheat. Overcharging generally results in high head pressure
and low superheat.
2. What is the primary purpose of superheat in a refrigeration system?
A. To prevent liquid refrigerant from entering the compressor
B. To increase condenser efficiency
C. To reduce head pressure
D. To improve subcooling
Answer: A
,Superheat ensures that all refrigerant leaving the evaporator is in vapor form,
protecting the compressor from liquid slugging. Liquid refrigerant entering the
compressor can cause severe mechanical damage due to incompressibility.
While superheat affects efficiency indirectly, its primary safety function is
compressor protection. It does not directly control condenser operation or
subcooling levels.
3. Which refrigerant property determines its boiling point at a given pressure?
A. Enthalpy
B. Latent heat
C. Pressure-temperature relationship
D. Specific gravity
Answer: C
The pressure-temperature relationship defines the saturation point of a
refrigerant, which directly determines its boiling and condensing temperatures.
This relationship is fundamental to refrigeration cycle operation. Enthalpy and
latent heat describe energy changes, not boiling point conditions. Specific
gravity is unrelated to phase change behavior.
4. A split system has low head pressure and low suction pressure. What is the
most likely issue?
A. Dirty evaporator coil
B. Overcharged system
C. Low ambient temperature affecting condenser
D. Restricted liquid line
Answer: C
Low ambient temperatures can reduce condenser pressure significantly, which in
turn lowers overall system pressures on both high and low sides. This is common
in cold weather operation without proper head pressure controls. A restricted
,liquid line would typically raise head pressure and lower suction pressure.
Overcharge would increase head pressure rather than reduce it.
5. What tool is primarily used to measure static pressure in duct systems?
A. Psychrometer
B. Manometer
C. Anemometer
D. Thermometer
Answer: B
A manometer is designed to measure air pressure differences within duct
systems, making it essential for evaluating static pressure. Psychrometers
measure humidity, not pressure. Anemometers measure air velocity, and
thermometers measure temperature. Static pressure readings are critical for
airflow diagnostics.
6. What is the function of a thermostatic expansion valve (TXV)?
A. Controls compressor speed
B. Regulates refrigerant flow into evaporator
C. Increases condenser pressure
D. Removes moisture from refrigerant
Answer: B
A TXV regulates the flow of refrigerant entering the evaporator based on
superheat demand. It ensures optimal evaporator performance by matching
refrigerant flow with heat load. It does not control compressor operation or
condenser pressure directly. Moisture removal is handled by filter driers.
7. Which condition indicates a restricted metering device?
A. High suction pressure and low superheat
, B. Low suction pressure and low head pressure
C. High head pressure and high superheat
D. Equalized system pressures
Answer: B
A restriction at the metering device limits refrigerant flow into the evaporator,
resulting in low suction pressure and low head pressure due to reduced system
circulation. Superheat typically rises, but in early restriction stages, it may
remain low. High head pressure is not typical of a restriction; it is more
associated with condenser issues. Equalized pressures suggest a non-running
system.
8. What does a capacitor primarily do in an HVAC motor circuit?
A. Stores and releases electrical energy
B. Converts AC to DC power
C. Reduces voltage permanently
D. Increases resistance
Answer: A
A capacitor stores electrical energy and releases it to create phase shift
necessary for motor starting and operation. This is essential for single-phase
motors used in HVAC systems. It does not convert AC to DC or permanently alter
voltage. It also does not function as a resistive device.
9. What is the primary purpose of subcooling?
A. Prevent compressor overheating
B. Ensure liquid refrigerant purity
C. Confirm full condenser condensation
D. Increase evaporator temperature
Answer: C
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. A technician measures a refrigerant system with low suction pressure and
high superheat. What is the most likely cause?
A. Overcharged system
B. Undercharged system
C. Dirty condenser coil
D. Faulty reversing valve
Answer: B
A low suction pressure combined with high superheat typically indicates that the
evaporator is being starved of refrigerant, which is a classic symptom of an
undercharged system. With insufficient refrigerant mass flow, the evaporator
cannot maintain proper saturation, leading to excessive temperature rise in the
suction line. While a dirty condenser can raise head pressure, it does not usually
produce high superheat. Overcharging generally results in high head pressure
and low superheat.
2. What is the primary purpose of superheat in a refrigeration system?
A. To prevent liquid refrigerant from entering the compressor
B. To increase condenser efficiency
C. To reduce head pressure
D. To improve subcooling
Answer: A
,Superheat ensures that all refrigerant leaving the evaporator is in vapor form,
protecting the compressor from liquid slugging. Liquid refrigerant entering the
compressor can cause severe mechanical damage due to incompressibility.
While superheat affects efficiency indirectly, its primary safety function is
compressor protection. It does not directly control condenser operation or
subcooling levels.
3. Which refrigerant property determines its boiling point at a given pressure?
A. Enthalpy
B. Latent heat
C. Pressure-temperature relationship
D. Specific gravity
Answer: C
The pressure-temperature relationship defines the saturation point of a
refrigerant, which directly determines its boiling and condensing temperatures.
This relationship is fundamental to refrigeration cycle operation. Enthalpy and
latent heat describe energy changes, not boiling point conditions. Specific
gravity is unrelated to phase change behavior.
4. A split system has low head pressure and low suction pressure. What is the
most likely issue?
A. Dirty evaporator coil
B. Overcharged system
C. Low ambient temperature affecting condenser
D. Restricted liquid line
Answer: C
Low ambient temperatures can reduce condenser pressure significantly, which in
turn lowers overall system pressures on both high and low sides. This is common
in cold weather operation without proper head pressure controls. A restricted
,liquid line would typically raise head pressure and lower suction pressure.
Overcharge would increase head pressure rather than reduce it.
5. What tool is primarily used to measure static pressure in duct systems?
A. Psychrometer
B. Manometer
C. Anemometer
D. Thermometer
Answer: B
A manometer is designed to measure air pressure differences within duct
systems, making it essential for evaluating static pressure. Psychrometers
measure humidity, not pressure. Anemometers measure air velocity, and
thermometers measure temperature. Static pressure readings are critical for
airflow diagnostics.
6. What is the function of a thermostatic expansion valve (TXV)?
A. Controls compressor speed
B. Regulates refrigerant flow into evaporator
C. Increases condenser pressure
D. Removes moisture from refrigerant
Answer: B
A TXV regulates the flow of refrigerant entering the evaporator based on
superheat demand. It ensures optimal evaporator performance by matching
refrigerant flow with heat load. It does not control compressor operation or
condenser pressure directly. Moisture removal is handled by filter driers.
7. Which condition indicates a restricted metering device?
A. High suction pressure and low superheat
, B. Low suction pressure and low head pressure
C. High head pressure and high superheat
D. Equalized system pressures
Answer: B
A restriction at the metering device limits refrigerant flow into the evaporator,
resulting in low suction pressure and low head pressure due to reduced system
circulation. Superheat typically rises, but in early restriction stages, it may
remain low. High head pressure is not typical of a restriction; it is more
associated with condenser issues. Equalized pressures suggest a non-running
system.
8. What does a capacitor primarily do in an HVAC motor circuit?
A. Stores and releases electrical energy
B. Converts AC to DC power
C. Reduces voltage permanently
D. Increases resistance
Answer: A
A capacitor stores electrical energy and releases it to create phase shift
necessary for motor starting and operation. This is essential for single-phase
motors used in HVAC systems. It does not convert AC to DC or permanently alter
voltage. It also does not function as a resistive device.
9. What is the primary purpose of subcooling?
A. Prevent compressor overheating
B. Ensure liquid refrigerant purity
C. Confirm full condenser condensation
D. Increase evaporator temperature
Answer: C
