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KENTUCKY – MASTER HVAC CONTRACTOR LICENSE
EXAM – HVAC QUESTIONS FORM REAL EXAMS
LATEST 2026 UPDATE WITH 150 QUESTIONS &
100% CORRECT DETAILED ANSWERS GRADED A+
(BRAND NEW!!)
Content covered (most tested areas): Load
calculations (Manual J), duct design (Manual D),
refrigeration cycle & components, electrical controls &
motors, gas furnaces & combustion, ventilation & indoor
air quality, codes & safety, hydronics, heat pumps,
installation practices, troubleshooting, EPA refrigerant
handling.
- What is the primary purpose of a Manual J calculation? A. Size duct insulation B. Determine building heat loss and gain C. Select thermostat location D. Calculate refrigerant charge
B. Determine building heat loss and gain
Manual J is the ACCA method used to determine heating and cooling loads.
- Superheat is defined as: A. Temperature above condensing temperature B. Temperature below saturation temperature C. Temperature of liquid refrigerant D. Temperature above saturation temperature of vapor
D. Temperature above saturation temperature of vapor
Superheat measures how much vapor temperature exceeds its boiling point.
- A cracked heat exchanger primarily presents which hazard? A. Refrigerant leak B. Carbon monoxide exposure C. Electrical short D. Airflow restriction
B. Carbon monoxide exposure
Cracks allow combustion gases to enter the supply air.
- The common voltage for residential control circuits is: A. 120 V B. 208 V C. 24 V D. 480 V
C. 24 V
Most thermostats and relays operate on 24-volt control power.
- The device that meters refrigerant into the evaporator is the: A. Accumulator B. Receiver C. Metering device D. Oil separator
C. Metering device
TXV or fixed orifice controls refrigerant flow and pressure drop.
- Static pressure in ducts refers to: A. Air temperature B. Air velocity C. Pressure exerted equally in all directions D. Noise level
C. Motor overheating
Frequent starts prevent proper cooling of the motor windings. 11.The reversing valve in a heat pump switches: A. Voltage B. Refrigerant flow direction C. Airflow D. Compressor speed
B. Refrigerant flow direction
This allows heating or cooling operation. 12.Subcooling is measured on the: A. Suction line B. Liquid line C. Discharge line D. Capillary tube
B. Liquid line
Subcooling indicates liquid refrigerant below saturation temperature. 13.High head pressure may be caused by: A. Dirty condenser coil B. Low refrigerant charge C. Oversized evaporator D. Low outdoor temperature
A. Dirty condenser coil
Restricted heat rejection raises condensing pressure. 14.A contactor is controlled by: A. Line voltage B. Control voltage C. Ground wire D. Neutral current
B. Control voltage
Typically 24 V energizes the coil to close contacts. 15.The minimum clearance around gas furnaces is specified by: A. Manufacturer instructions B. Utility company C. Thermostat manual D. Duct design guide
A. Manufacturer instructions
Codes require following listed clearances. 16.Manual D addresses: A. Load calculation B. Equipment selection C. Duct design D. Refrigerant piping
C. Duct design
Manual D provides methods for sizing duct systems. 17.A dirty air filter causes: A. Increased airflow B. Reduced static pressure C. Reduced airflow D. Higher voltage
C. Reduced airflow
Clogged filters restrict air movement. 18.The compressor oil returns primarily through the: A. Liquid line B. Suction line C. Capillary tube D. Receiver
C. Water as heat transfer medium
Hot water circulates to deliver heat. 23.The purpose of a trap in a condensate line is to: A. Stop airflow bypass B. Increase pressure C. Prevent freezing D. Remove debris
A. Stop airflow bypass
Prevents air from being pulled through the drain. 24.Locked rotor amps occur when: A. Motor runs normally B. Motor cannot start C. Voltage is low only D. Capacitor is oversized
B. Motor cannot start
Rotor is stationary while full current flows. 25.The dew point is the temperature at which: A. Air becomes saturated B. Water boils C. Ice melts D. Pressure increases
A. Air becomes saturated
Moisture condenses at this temperature. 26.A belt-driven blower allows adjustment of: A. Voltage B. Airflow speed C. Refrigerant pressure D. Combustion rate
B. Airflow speed
Pulley changes alter fan RPM. 27.EPA Section 608 regulates: A. Electrical licensing B. Refrigerant handling C. Gas piping D. Duct leakage
B. Refrigerant handling
Certification required for refrigerant work. 28.A normally open switch is one that: A. Conducts at all times B. Opens when energized C. Is open until actuated D. Has no terminals
C. Is open until actuated
Closes only when triggered. 29.Combustion air is needed to: A. Cool burners B. Supply oxygen for burning C. Increase pressure D. Reduce noise
B. Supply oxygen for burning
Proper combustion requires adequate oxygen. 30.The evaporator coil is located: A. Before compressor B. In the conditioned air stream C. Outdoors only D. In the gas line
C. Evaporator
Heat absorption causes boiling. 35.Low suction pressure may indicate: A. Overcharge B. Dirty condenser C. Undercharge D. High airflow
C. Undercharge
Insufficient refrigerant reduces evaporator pressure. 36.A disconnect switch is used to: A. Measure voltage B. Provide local power shutoff C. Increase current D. Control temperature
B. Provide local power shutoff
Required for servicing safety. 37.Heat pumps lose capacity as outdoor temperature: A. Increases B. Decreases C. Stays constant D. Reaches 75°F
B. Decreases
Less heat available to extract from cold air. 38.A backdraft condition is dangerous because it: A. Reduces airflow B. Causes overheating C. Pulls exhaust gases indoors D. Increases humidity
C. Pulls exhaust gases indoors
Can lead to carbon monoxide exposure. 39.A zoning system controls: A. Refrigerant type B. Air distribution to areas C. Compressor oil D. Gas pressure
B. Air distribution to areas
Dampers regulate airflow to zones. 40.The purpose of insulation on suction lines is to: A. Increase pressure B. Prevent heat gain and condensation C. Strengthen pipe D. Reduce oil flow
B. Prevent heat gain and condensation
Keeps refrigerant cool and stops sweating. 41.A transformer changes: A. Frequency B. Voltage C. Resistance D. Current type
B. Voltage
Steps voltage up or down. 42.Purging nitrogen during brazing prevents: A. Corrosion inside tubing B. Pressure buildup C. Noise D. Airflow issues
B. High temperature
Shuts burner off if overheating occurs. 47.An ECM motor is known for: A. Fixed speed only B. High energy consumption C. Variable speed efficiency D. No electronics
C. Variable speed efficiency
Electronically controlled for optimal airflow. 48.The condenser rejects heat to: A. Indoor air B. Ground only C. Outdoor air or water D. Refrigerant oil
C. Outdoor air or water
Removes absorbed indoor heat. 49.Proper refrigerant recovery prevents: A. Equipment damage only B. Environmental harm C. Noise issues D. Airflow problems
B. Environmental harm
Protects ozone and climate. 50.The thermostat anticipator reduces: A. Humidity B. Temperature overshoot C. Voltage drop D. Air velocity
B. Temperature overshoot
Preheats circuit to stop heating early and stabilize room temperature. 51.The primary purpose of a receiver in a refrigeration system is to: A. Store excess liquid refrigerant B. Increase suction pressure C. Remove oil from vapor D. Cool discharge gas
A. Store excess liquid refrigerant
Receivers hold liquid refrigerant to ensure steady supply to the metering device. 52.A heat pump in defrost mode temporarily operates as: A. Electric heater only B. Air conditioner C. Gas furnace D. Boiler
B. Air conditioner
Reverses to cooling to warm the outdoor coil and melt frost. 53.The most common cause of evaporator coil icing is: A. High airflow B. Dirty condenser C. Low airflow D. High ambient temperature
C. Low airflow
Restricted airflow causes coil temperature to drop below freezing. 54.A megohmmeter is used to test: A. Voltage output B. Current draw C. Insulation resistance
C. Ohm
Ohm measures opposition to current flow. 59.Excessive superheat indicates: A. Overfeeding evaporator B. Floodback C. Starved evaporator D. High subcooling
C. Starved evaporator
Not enough refrigerant is entering the coil. 60.A barometric damper is used to: A. Control indoor humidity B. Regulate draft in flue C. Adjust gas pressure D. Reduce noise
B. Regulate draft in flue
Maintains proper combustion airflow. 61.A three-phase motor compared to single-phase is typically: A. Less efficient B. More complex to wire C. Smoother running D. Lower torque
C. Smoother running
Three-phase power provides constant torque. 62.A vacuum pump removes: A. Oil only B. Air and moisture C. Refrigerant only D. Dirt particles
B. Air and moisture
Essential before charging refrigerant. 63.The purpose of subcooling measurement is to determine: A. Airflow rate B. Liquid refrigerant condition C. Motor efficiency D. Gas pressure
B. Liquid refrigerant condition
Confirms solid liquid at metering device. 64.A fan cycling switch controls: A. Compressor oil B. Condenser fan operation C. Indoor blower speed D. Gas valve timing
B. Condenser fan operation
Maintains proper head pressure. 65.A cracked flue pipe can cause: A. Reduced efficiency only B. Water leakage C. Carbon monoxide entry D. Increased airflow
C. Carbon monoxide entry
Leaking exhaust gases pose serious hazard. 66.The evaporator removes heat by: A. Conduction only B. Radiation only C. Refrigerant evaporation D. Compression
B. Outdoor air for cooling
“Free cooling” when outdoor conditions allow. 71.A heat anticipator is found in: A. Compressor B. Thermostat C. Gas valve D. Contactor
B. Thermostat
Prevents overshoot in heating mode. 72.The most accurate way to charge a TXV system is by: A. Superheat B. Subcooling C. Pressure only D. Sight glass
B. Subcooling
TXV controls superheat, so subcooling verifies charge. 73.A scroll compressor differs from reciprocating by: A. Using pistons B. Having fewer moving parts C. Requiring oil pump D. Producing more vibration
B. Having fewer moving parts
Scrolls are smoother and quieter. 74.The primary purpose of ventilation codes is to: A. Reduce equipment size B. Protect indoor air quality C. Increase humidity D. Improve aesthetics
B. Protect indoor air quality
Ensures fresh air and contaminant removal. 75.An open winding in a motor results in: A. Normal operation B. Reduced voltage C. No current flow D. Excessive airflow
C. No current flow
Circuit is incomplete. 76.The condenser fan motor failure will likely cause: A. Low head pressure B. High head pressure C. Low suction pressure only D. No change
B. High head pressure
Heat cannot be rejected outdoors. 77.A sight glass with bubbles usually indicates: A. Overcharge B. Undercharge or restriction C. Normal condition always D. High airflow
B. Undercharge or restriction
Liquid line not fully filled. 78.The unit of power is: A. Volt B. Amp C. Watt D. Ohm
