TEXAS COMMERCIAL HVAC
CERTIFICATION EXAM WITH ACTUAL
QUESTIONS AND VERIFIED ANSWERS,
PLUS EXPLAINED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED 100% PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
1. A newly installed 20-ton commercial rooftop unit consistently trips
the high-pressure safety during hot afternoons. The condenser coil
is clean, condenser fan motors are operating at proper speed, and
airflow across the evaporator is correct. Which condition is the
MOST likely cause?
A. Undercharged refrigerant system
B. Non-condensable gases in the refrigerant circuit
C. Low return air temperature
D. Restricted liquid line filter-drier
Answer: B. Non-condensable gases in the refrigerant circuit
Rationale: Non-condensable gases such as air increase condensing
pressure by occupying space within the condenser, causing excessive
head pressure despite proper airflow and clean coils. Undercharging
generally lowers head pressure, while a restricted liquid line primarily
causes flashing and low evaporator performance.
2. During commissioning of a variable air volume (VAV) system,
static pressure in the supply duct remains unstable despite all VAV
boxes functioning correctly. Which control component should be
inspected FIRST?
1
,A. Return air smoke detector
B. Supply duct static pressure sensor
C. Mixed air temperature sensor
D. Economizer actuator
Answer: B. Supply duct static pressure sensor
Rationale: The VFD controlling the supply fan relies directly on the
static pressure sensor. A faulty sensor causes unstable fan speed
adjustments, producing fluctuating duct pressure.
3. According to commercial refrigeration principles, excessive
compressor superheat primarily indicates:
A. Floodback to compressor
B. Insufficient evaporator refrigerant feed
C. Excessive condenser airflow
D. High ambient humidity
Answer: B. Insufficient evaporator refrigerant feed
Rationale: High compressor superheat means refrigerant has absorbed
excessive sensible heat before reaching the compressor, typically caused
by insufficient refrigerant flow through the evaporator.
4. A technician measures:
Suction pressure: Low
Head pressure: Low
Superheat: High
Subcooling: Low
Which diagnosis is MOST accurate?
2
,A. Dirty evaporator coil
B. Refrigerant overcharge
C. Refrigerant undercharge
D. Condenser airflow restriction
Answer: C. Refrigerant undercharge
Rationale: Low suction, low head pressure, high superheat, and low
subcooling together are classic symptoms of an undercharged
refrigeration system.
5. What is the primary function of a crankcase heater on large
commercial scroll or reciprocating compressors?
A. Increase discharge pressure
B. Prevent oil foaming during operation
C. Prevent refrigerant migration into compressor oil
D. Increase compressor efficiency
Answer: C. Prevent refrigerant migration into compressor oil
Rationale: The crankcase heater keeps compressor oil warm during
shutdown, preventing refrigerant from condensing into the oil and
causing dilution or slugging during startup.
6. Which HVAC component directly controls latent heat removal?
A. Condenser fan
B. Expansion valve
C. Evaporator coil
D. Liquid receiver
Answer: C. Evaporator coil
3
, Rationale: Moisture condenses on the evaporator coil when its surface
temperature is below the air's dew point, removing latent heat.
7. A building automation system reports simultaneous heating and
cooling in multiple zones. Which issue is MOST likely?
A. Incorrect chilled water temperature
B. Faulty zone control sequences
C. Dirty condenser coil
D. Low condenser water flow
Answer: B. Faulty zone control sequences
Rationale: Improper BAS programming or malfunctioning control
sequences commonly result in simultaneous heating and cooling,
wasting significant energy.
8. The purpose of a discharge temperature sensor on a commercial
compressor is to:
A. Control evaporator pressure
B. Prevent compressor overheating
C. Regulate condenser fan speed
D. Measure liquid subcooling
Answer: B. Prevent compressor overheating
Rationale: High discharge temperatures can damage valves, oil, and
motor insulation. The sensor provides protection by shutting down the
compressor if temperatures exceed safe limits.
9. Which refrigerant condition produces the HIGHEST compressor
discharge temperature?
4
CERTIFICATION EXAM WITH ACTUAL
QUESTIONS AND VERIFIED ANSWERS,
PLUS EXPLAINED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED 100% PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
1. A newly installed 20-ton commercial rooftop unit consistently trips
the high-pressure safety during hot afternoons. The condenser coil
is clean, condenser fan motors are operating at proper speed, and
airflow across the evaporator is correct. Which condition is the
MOST likely cause?
A. Undercharged refrigerant system
B. Non-condensable gases in the refrigerant circuit
C. Low return air temperature
D. Restricted liquid line filter-drier
Answer: B. Non-condensable gases in the refrigerant circuit
Rationale: Non-condensable gases such as air increase condensing
pressure by occupying space within the condenser, causing excessive
head pressure despite proper airflow and clean coils. Undercharging
generally lowers head pressure, while a restricted liquid line primarily
causes flashing and low evaporator performance.
2. During commissioning of a variable air volume (VAV) system,
static pressure in the supply duct remains unstable despite all VAV
boxes functioning correctly. Which control component should be
inspected FIRST?
1
,A. Return air smoke detector
B. Supply duct static pressure sensor
C. Mixed air temperature sensor
D. Economizer actuator
Answer: B. Supply duct static pressure sensor
Rationale: The VFD controlling the supply fan relies directly on the
static pressure sensor. A faulty sensor causes unstable fan speed
adjustments, producing fluctuating duct pressure.
3. According to commercial refrigeration principles, excessive
compressor superheat primarily indicates:
A. Floodback to compressor
B. Insufficient evaporator refrigerant feed
C. Excessive condenser airflow
D. High ambient humidity
Answer: B. Insufficient evaporator refrigerant feed
Rationale: High compressor superheat means refrigerant has absorbed
excessive sensible heat before reaching the compressor, typically caused
by insufficient refrigerant flow through the evaporator.
4. A technician measures:
Suction pressure: Low
Head pressure: Low
Superheat: High
Subcooling: Low
Which diagnosis is MOST accurate?
2
,A. Dirty evaporator coil
B. Refrigerant overcharge
C. Refrigerant undercharge
D. Condenser airflow restriction
Answer: C. Refrigerant undercharge
Rationale: Low suction, low head pressure, high superheat, and low
subcooling together are classic symptoms of an undercharged
refrigeration system.
5. What is the primary function of a crankcase heater on large
commercial scroll or reciprocating compressors?
A. Increase discharge pressure
B. Prevent oil foaming during operation
C. Prevent refrigerant migration into compressor oil
D. Increase compressor efficiency
Answer: C. Prevent refrigerant migration into compressor oil
Rationale: The crankcase heater keeps compressor oil warm during
shutdown, preventing refrigerant from condensing into the oil and
causing dilution or slugging during startup.
6. Which HVAC component directly controls latent heat removal?
A. Condenser fan
B. Expansion valve
C. Evaporator coil
D. Liquid receiver
Answer: C. Evaporator coil
3
, Rationale: Moisture condenses on the evaporator coil when its surface
temperature is below the air's dew point, removing latent heat.
7. A building automation system reports simultaneous heating and
cooling in multiple zones. Which issue is MOST likely?
A. Incorrect chilled water temperature
B. Faulty zone control sequences
C. Dirty condenser coil
D. Low condenser water flow
Answer: B. Faulty zone control sequences
Rationale: Improper BAS programming or malfunctioning control
sequences commonly result in simultaneous heating and cooling,
wasting significant energy.
8. The purpose of a discharge temperature sensor on a commercial
compressor is to:
A. Control evaporator pressure
B. Prevent compressor overheating
C. Regulate condenser fan speed
D. Measure liquid subcooling
Answer: B. Prevent compressor overheating
Rationale: High discharge temperatures can damage valves, oil, and
motor insulation. The sensor provides protection by shutting down the
compressor if temperatures exceed safe limits.
9. Which refrigerant condition produces the HIGHEST compressor
discharge temperature?
4
