TEXAS RESIDENTIAL 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 residential split-system air conditioner in Texas
has a 3-ton cooling capacity. During commissioning, the measured
temperature split across the evaporator coil is only 10°F with
correct airflow. What is the most likely cause?
A. Dirty condenser coil
B. Low refrigerant charge
C. Oversized return duct
D. Defective contactor
Answer: B. Low refrigerant charge
Rationale: A properly charged residential air conditioning system
generally produces a temperature difference of approximately 18–22°F
across the evaporator under normal indoor conditions. A 10°F split
commonly indicates insufficient refrigerant, excessive airflow, or
compressor inefficiency. Since airflow is confirmed correct, low
refrigerant charge is the most probable cause.
2. Which superheat condition is most likely to damage a fixed-orifice
air conditioning system?
A. Excessively high superheat
B. Slightly low superheat
C. Normal superheat
D. Stable suction pressure
1
,Answer: A. Excessively high superheat
Rationale: High superheat indicates inadequate refrigerant reaching the
evaporator. The compressor receives excessively hot vapor, reducing
cooling and lubrication, increasing discharge temperatures, and
shortening compressor life.
3. During a heating call, a gas furnace inducer motor starts, but the
ignitor never energizes. Which safety device most likely prevented
ignition?
A. Flame sensor
B. Pressure switch
C. Fan limit switch
D. Blower relay
Answer: B. Pressure switch
Rationale: The pressure switch confirms proper inducer draft before
ignition. If it fails to close, the ignition sequence stops before energizing
the ignitor to prevent unsafe combustion.
4. What is the primary purpose of subcooling in an air conditioning
system?
A. Protect the evaporator motor
B. Ensure liquid refrigerant reaches the metering device
C. Increase compressor temperature
D. Reduce airflow
Answer: B. Ensure liquid refrigerant reaches the metering device
Rationale: Subcooling guarantees refrigerant remains in liquid form
before entering the expansion device. Flash gas in the liquid line
reduces system efficiency and capacity.
5. Which electrical instrument is safest for verifying absence of
voltage before replacing a contactor?
2
,A. Clamp ammeter only
B. Non-contact voltage tester only
C. Digital multimeter after verifying operation on a known source
D. Thermometer
Answer: C. Digital multimeter after verifying operation on a known
source
Rationale: The "live-dead-live" verification method ensures the meter is
functioning before confirming circuits are de-energized.
6. A PSC blower motor hums but does not rotate. What component
should be tested first?
A. Pressure switch
B. Capacitor
C. Flame sensor
D. Transformer
Answer: B. Capacitor
Rationale: A failed run capacitor is one of the most common causes of
PSC motor failure to start while producing an audible hum.
7. Refrigerant leaving the evaporator should normally be:
A. Saturated liquid
B. Superheated vapor
C. Subcooled liquid
D. Mixed liquid and vapor
Answer: B. Superheated vapor
Rationale: Only vapor should return to the compressor. Superheating
ensures no liquid refrigerant reaches the compressor, preventing
slugging.
8. Which component prevents reverse refrigerant flow when the
compressor shuts off in many systems?
3
, A. Filter drier
B. Check valve
C. Suction accumulator
D. Receiver
Answer: B. Check valve
Rationale: Check valves maintain directional refrigerant flow and
prevent migration where applicable.
9. What does a clogged liquid-line filter drier typically cause?
A. High suction pressure
B. Flash gas before the metering device
C. Increased evaporator airflow
D. Low compressor amperage only
Answer: B. Flash gas before the metering device
Rationale: A restriction causes pressure drop, allowing refrigerant to
partially vaporize before reaching the expansion device.
10. The purpose of the TXV sensing bulb is to:
A. Measure condenser temperature
B. Control evaporator superheat
C. Measure room temperature
D. Control blower speed
Answer: B. Control evaporator superheat
Rationale: The sensing bulb monitors suction line temperature and
modulates valve opening to maintain proper superheat.
11. Which airflow condition is most likely to cause evaporator
icing?
A. Excessive airflow
B. Low airflow across the coil
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 residential split-system air conditioner in Texas
has a 3-ton cooling capacity. During commissioning, the measured
temperature split across the evaporator coil is only 10°F with
correct airflow. What is the most likely cause?
A. Dirty condenser coil
B. Low refrigerant charge
C. Oversized return duct
D. Defective contactor
Answer: B. Low refrigerant charge
Rationale: A properly charged residential air conditioning system
generally produces a temperature difference of approximately 18–22°F
across the evaporator under normal indoor conditions. A 10°F split
commonly indicates insufficient refrigerant, excessive airflow, or
compressor inefficiency. Since airflow is confirmed correct, low
refrigerant charge is the most probable cause.
2. Which superheat condition is most likely to damage a fixed-orifice
air conditioning system?
A. Excessively high superheat
B. Slightly low superheat
C. Normal superheat
D. Stable suction pressure
1
,Answer: A. Excessively high superheat
Rationale: High superheat indicates inadequate refrigerant reaching the
evaporator. The compressor receives excessively hot vapor, reducing
cooling and lubrication, increasing discharge temperatures, and
shortening compressor life.
3. During a heating call, a gas furnace inducer motor starts, but the
ignitor never energizes. Which safety device most likely prevented
ignition?
A. Flame sensor
B. Pressure switch
C. Fan limit switch
D. Blower relay
Answer: B. Pressure switch
Rationale: The pressure switch confirms proper inducer draft before
ignition. If it fails to close, the ignition sequence stops before energizing
the ignitor to prevent unsafe combustion.
4. What is the primary purpose of subcooling in an air conditioning
system?
A. Protect the evaporator motor
B. Ensure liquid refrigerant reaches the metering device
C. Increase compressor temperature
D. Reduce airflow
Answer: B. Ensure liquid refrigerant reaches the metering device
Rationale: Subcooling guarantees refrigerant remains in liquid form
before entering the expansion device. Flash gas in the liquid line
reduces system efficiency and capacity.
5. Which electrical instrument is safest for verifying absence of
voltage before replacing a contactor?
2
,A. Clamp ammeter only
B. Non-contact voltage tester only
C. Digital multimeter after verifying operation on a known source
D. Thermometer
Answer: C. Digital multimeter after verifying operation on a known
source
Rationale: The "live-dead-live" verification method ensures the meter is
functioning before confirming circuits are de-energized.
6. A PSC blower motor hums but does not rotate. What component
should be tested first?
A. Pressure switch
B. Capacitor
C. Flame sensor
D. Transformer
Answer: B. Capacitor
Rationale: A failed run capacitor is one of the most common causes of
PSC motor failure to start while producing an audible hum.
7. Refrigerant leaving the evaporator should normally be:
A. Saturated liquid
B. Superheated vapor
C. Subcooled liquid
D. Mixed liquid and vapor
Answer: B. Superheated vapor
Rationale: Only vapor should return to the compressor. Superheating
ensures no liquid refrigerant reaches the compressor, preventing
slugging.
8. Which component prevents reverse refrigerant flow when the
compressor shuts off in many systems?
3
, A. Filter drier
B. Check valve
C. Suction accumulator
D. Receiver
Answer: B. Check valve
Rationale: Check valves maintain directional refrigerant flow and
prevent migration where applicable.
9. What does a clogged liquid-line filter drier typically cause?
A. High suction pressure
B. Flash gas before the metering device
C. Increased evaporator airflow
D. Low compressor amperage only
Answer: B. Flash gas before the metering device
Rationale: A restriction causes pressure drop, allowing refrigerant to
partially vaporize before reaching the expansion device.
10. The purpose of the TXV sensing bulb is to:
A. Measure condenser temperature
B. Control evaporator superheat
C. Measure room temperature
D. Control blower speed
Answer: B. Control evaporator superheat
Rationale: The sensing bulb monitors suction line temperature and
modulates valve opening to maintain proper superheat.
11. Which airflow condition is most likely to cause evaporator
icing?
A. Excessive airflow
B. Low airflow across the coil
4
