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CONNECTICUT – HVAC CONTRACTOR LICENSE EXAM –
HVAC MOCK EXAM QUESTIONS FORM REAL EXAMS
LATEST 2026 UPDATE WITH 150 QUESTIONS & 100%
CORRECT DETAILED ANSWERS GRADED A+ (BRAND
NEW!!)
Content covered (most tested areas):
Refrigeration cycle • Electrical fundamentals • Controls &
thermostats • Duct design & airflow • Load calculations • Gas
heating systems • Oil heating systems • Heat pumps • Venting
& combustion air • Codes & safety • Installation practices •
Troubleshooting • EPA refrigerant handling • Hydronics basics
- The primary purpose of a condenser in a refrigeration system is to: A. Increase refrigerant pressure only B. Absorb heat from indoor air
C. Reject heat to the outside air
D. Meter refrigerant flow It removes heat from the refrigerant, condensing vapor into liquid.
- Superheat is measured at the: A. Condenser outlet B. Compressor discharge
C. Evaporator outlet
D. Receiver tank Superheat confirms full vaporization leaving the evaporator.
- Subcooling occurs in the: A. Evaporator
B. Compressor C. Metering device
D. Condenser
Liquid refrigerant is cooled below saturation after condensing.
- A normally closed relay contact will be: A. Open when de-energized
B. Closed when de-energized
C. Always open D. Always closed NC contacts pass current until energized.
- The unit of electrical resistance is: A. Volt B. Watt C. Ampere
D. Ohm
Ohm measures opposition to current flow.
- A capacitor in a single-phase motor primarily: A. Reduces voltage
B. Creates phase shift for starting torque
C. Increases resistance D. Stores mechanical energy Phase shift enables rotating magnetic field.
- Low airflow across an evaporator typically causes: A. High superheat B. Low head pressure
C. Evaporator icing
D. Compressor overheating only Reduced heat load drops coil temperature below freezing.
D. Neither mode Most systems energize in cooling. 13.AFUE measures efficiency of: A. Air conditioners B. Heat pumps C. Boilers only
D. Furnaces over a heating season
Annual Fuel Utilization Efficiency applies to fuel-burning furnaces. 14.Combustion air is required to: A. Cool the heat exchanger
B. Provide oxygen for proper burning
C. Increase flue temperature D. Reduce draft Insufficient air leads to incomplete combustion. 15.Carbon monoxide is dangerous because it: A. Smells strong B. Irritates lungs C. Is heavier than air only
D. Binds to hemoglobin in blood
It prevents oxygen transport in the body. 16.Draft in a chimney is created by: A. Wind pressure only B. Mechanical fans only
C. Temperature difference between flue gases and
outside air
D. Gas valve pressure Hot gases rise, producing natural draft.
17.The purpose of a barometric damper is to: A. Block airflow B. Increase draft
C. Regulate draft automatically
D. Prevent backflow entirely It maintains stable combustion conditions. 18.Oil burners atomize fuel using: A. Gravity feed B. Electric heating
C. High pressure through a nozzle
D. Ultrasonic vibration Pressure forces oil into fine spray. 19.A cracked heat exchanger can cause: A. Low efficiency only B. Fuel shortage
C. Flue gases entering living space
D. Reduced airflow only This creates serious safety hazards. 20.Static pressure in ductwork refers to: A. Air velocity B. Air temperature
C. Resistance to airflow
D. Humidity level Higher resistance increases static pressure. 21.Flexible ducts should be installed: A. Fully compressed B. With sharp bends
C. Fully stretched with gentle turns
C. Moisture phase change
D. Air velocity Evaporation or condensation involves latent heat. 27.A psychrometer measures: A. Pressure B. Voltage
C. Relative humidity
D. Airflow only Uses wet-bulb and dry-bulb temperatures. 28.Hydronic systems transfer heat using: A. Refrigerant vapor B. Air only C. Oil only
D. Water or glycol solution
Hot water circulates through piping. 29.Cavitation in pumps is caused by: A. High discharge pressure B. Low motor speed
C. Insufficient inlet pressure
D. Excess lubrication Vapor bubbles collapse inside pump. 30.A zone valve in hydronics controls: A. Temperature of water B. Pressure of water
C. Flow to a specific heating zone
D. Boiler firing rate Allows independent room control.
31.The purpose of a relief valve on a boiler is to: A. Increase pressure B. Reduce temperature only
C. Prevent excessive pressure buildup
D. Stop circulation Safety device to avoid explosion. 32.Electrical power (watts) equals: A. Volts ÷ amps B. Ohms × volts
C. Volts × amps
D. Amps ÷ volts Basic electrical power formula. 33.A grounded system protects against: A. Overheating B. Overvoltage
C. Electrical shock
D. Power loss Provides safe path to earth. 34.A contactor is used to: A. Measure current B. Store energy
C. Switch high current loads electrically
D. Reduce voltage Common in compressors and motors. 35.Locked rotor amperage (LRA) occurs when: A. Motor runs normally B. Motor is off
C. Motor cannot turn at startup
C. High head pressure
D. Reduced discharge temperature Poor heat rejection increases pressure. 41.A crankcase heater prevents: A. Compressor overheating B. Oil foaming only
C. Refrigerant migration into oil
D. Liquid floodback during operation Keeps oil warm during off cycles. 42.A check valve allows flow: A. Both directions B. No direction C. Variable direction
D. One direction only
Prevents reverse flow. 43.A solenoid valve operates using: A. Hydraulic pressure B. Thermal expansion
C. Electromagnetic force
D. Gravity Electric coil moves plunger. 44.Defrost in heat pumps removes: A. Indoor moisture B. Dust buildup
C. Ice from outdoor coil
D. Excess refrigerant Maintains heat transfer efficiency.
45.Electric resistance heat converts energy at about: A. 50% efficiency B. 75% efficiency C. 90% efficiency
D. Nearly 100% efficiency
Almost all electrical energy becomes heat. 46.A flame sensor proves: A. Gas pressure B. Airflow
C. Presence of burner flame
D. Draft level Safety device to shut gas if flame fails. 47.Short cycling of a furnace can be caused by: A. Low voltage only B. Clean filter
C. Overheating due to restricted airflow
D. Excess combustion air High limit switch trips repeatedly. 48.A manometer measures: A. Temperature B. Voltage C. Humidity
D. Pressure difference
Used for gas pressure and static pressure. 49.Proper refrigerant charge ensures: A. Minimum airflow B. Maximum noise
C. Efficient system performance
54.Phase imbalance can cause motors to: A. Run cooler B. Increase efficiency
C. Overheat and fail prematurely
D. Reduce amperage Unequal voltages stress windings. 55.A VFD controls motor speed by varying: A. Resistance B. Current only C. Voltage only
D. Frequency (and voltage)
Speed is proportional to frequency. 56.The purpose of a transformer is to: A. Store electrical energy B. Convert AC to DC
C. Change voltage levels
D. Increase frequency Commonly steps down to 24V control power. 57.Control circuits in HVAC systems typically operate at: A. 240 V B. 120 V C. 480 V
D. 24 V
Low voltage improves safety. 58.A float switch in a condensate pan prevents: A. Freezing B. Overheating
C. Water overflow damage
D. Air leakage Shuts system off when pan fills. 59.Dirty air filters can cause: A. Low static pressure B. High airflow
C. Reduced airflow and overheating
D. Lower energy use Restricted filters strain systems. 60.A high-efficiency furnace typically uses: A. Natural draft only B. Masonry chimney only
C. Sealed combustion with PVC venting
D. No venting Condensing furnaces use plastic flues. 61.Condensing furnaces extract additional heat from: A. Incoming air B. Burner flame
C. Water vapor in exhaust gases
D. Electrical components Latent heat recovery increases efficiency. 62.Gas pressure for natural gas appliances is commonly about: A. 0.5 inches WC B. 2 inches WC
C. 3.5 inches WC
D. 14 inches WC Standard manifold pressure. 63.Propane manifold pressure is typically about: A. 2 inches WC B. 3.5 inches WC
68.Oil burner electrodes are used to: A. Control airflow B. Heat oil
C. Ignite fuel spray
D. Measure pressure Produce high-voltage spark. 69.Heat anticipators in thermostats prevent: A. Overcooling B. Compressor damage
C. Temperature overshoot in heating
D. Power surges Shuts system off slightly early. 70.Programmable thermostats save energy by: A. Increasing airflow B. Running continuously
C. Adjusting temperature schedules
D. Increasing humidity Reduces runtime during unoccupied periods. 71.A zoning system uses dampers to: A. Reduce noise only B. Increase humidity
C. Control airflow to different areas
D. Increase static pressure intentionally Improves comfort and efficiency. 72.A bypass damper prevents: A. Low airflow B. High humidity
C. Excessive static pressure in zoned systems
D. Energy loss only Protects blower and ducts. 73.The purpose of return air ducts is to: A. Supply fresh air only B. Remove combustion gases
C. Carry air back to the air handler
D. Increase pressure Completes air circulation loop. 74.Outdoor air intakes provide: A. Cooling only B. Dehumidification only
C. Ventilation for indoor air quality
D. Heating Dilutes indoor contaminants. 75.Economizers reduce cooling costs by using: A. Refrigerant only B. Heating coils
C. Cool outdoor air
D. Higher compressor speed “Free cooling” when conditions allow. 76.A humidifier adds: A. Heat B. Pressure
C. Moisture to air
D. Oxygen Improves comfort in dry conditions. 77.A dehumidifier removes moisture by: A. Heating air B. Venting outside only
82.Oil separators are installed to: A. Remove moisture B. Increase pressure
C. Return oil to compressor
D. Improve airflow Prevents oil loss in system. 83.Sight glass moisture indicators change color to show: A. Temperature B. Pressure
C. Presence of moisture
D. Oil level Helps identify contamination. 84.Vacuum pumps remove: A. Oil only B. Refrigerant only
C. Air and moisture from system
D. Dirt particles Essential before charging. 85.A deep vacuum is measured in: A. PSI B. Inches of water column C. Volts
D. Microns
Indicates level of evacuation. 86.Charging refrigerant by weight is most accurate when: A. System is running B. Using pressure only
C. Factory charge specification is known
D. Temperature is ignored Manufacturers provide exact amounts. 87.Line sets should be insulated to prevent: A. High pressure B. Oil return
C. Condensation and energy loss
D. Voltage drop Especially important on suction lines. 88.Brazing refrigerant lines requires: A. Solder only B. No heat
C. High-temperature brazing alloy
D. Adhesive Produces strong leak-free joints. 89.Nitrogen purging during brazing prevents: A. Oxidation inside tubing B. Overheating C. Refrigerant loss D. Pressure drop
A. Oxidation inside tubing
Prevents scale that can clog components. 90.Pressure testing a system checks for: A. Electrical faults B. Airflow problems
C. Leaks in piping
D. Thermostat operation Ensures system integrity. 91.A high-pressure switch protects against: A. Low airflow
