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Free HVAC Fundamentals Practice practice questions (2026)

What is the format? These ten original multiple-choice questions introduce HVAC Fundamentals Practice study topics. They are practice material, not actual exam items. Official assessments may use different formats; check the current candidate guide for your credential.

What does this prepare me for? General code practice. Not aligned to any specific state exam blueprint. Check your licensing authority’s current bulletin. CodeReady does not confer a license.

What should I study? Start with refrigeration cycle and components, electrical and motors, airflow and duct design. This bank uses Fundamentals; IMC 2021 / IFGC 2021 / NEC 440 references. Check the current exam objectives, adopted editions, and permitted references before planning your study.

How should I practice? Choose an answer before opening the explanation. Read the cited reference and revisit unfamiliar topics. These samples are general preparation, not jurisdiction-specific advice.

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1 / Refrigeration cycle and components

In a conventional vapor-compression cooling system, which component absorbs heat from the air being cooled?

  1. Condenser
  2. Compressor
  3. Evaporator
  4. Liquid receiver
Show answer & explanation

Evaporator

Refrigerant evaporates at low pressure in the evaporator, taking heat from the air passing over the coil.

ASHRAE Fundamentals — thermodynamics and refrigeration cycles

2 / Refrigeration cycle and components

Why is an externally equalized TXV used where the evaporator and distributor have significant pressure drop?

  1. To hold suction pressure equal to discharge pressure
  2. To connect condenser pressure to the bulb
  3. To eliminate the need for a sensing bulb
  4. To sense evaporator outlet pressure for superheat control
Show answer & explanation

To sense evaporator outlet pressure for superheat control

External equalization accounts for outlet pressure rather than using a higher inlet pressure that could cause excessive outlet superheat.

ASHRAE Handbook—Refrigeration — refrigerant control devices and system practices

3 / Electrical and motors

A 24 V control circuit has an open series switch. What happens to current through that series path?

  1. It doubles because the circuit resistance drops
  2. It continues unchanged through the load
  3. It stops flowing
  4. It falls by half because only one switch is open
Show answer & explanation

It stops flowing

An open circuit breaks the conductive path. Voltage can remain present across the opening even though series current is zero.

Trade math — electrical circuit and motor fundamentals

4 / Electrical and motors

An air conditioner nameplate lists MCA 24 A and maximum overcurrent protection 40 A. Which statement correctly distinguishes these markings?

  1. Both markings are maximum permissible conductor ampacities
  2. MCA is the maximum permitted breaker size
  3. MCA guides minimum conductor ampacity; MOCP limits the permitted protective-device rating
  4. MOCP is the compressor's normal running current
Show answer & explanation

MCA guides minimum conductor ampacity; MOCP limits the permitted protective-device rating

Minimum circuit ampacity and maximum overcurrent protection serve different purposes. Apply conductor correction factors, terminal limits, and the specified protective-device type.

Manufacturer data (typical) — use the equipment-specific service instructions

5 / Airflow and duct design

A duct design allows 0.30 in. w.c. for duct friction over a total effective length of 150 ft. What friction rate should be used per 100 ft?

  1. 0.30 in. w.c. per 100 ft
  2. 0.45 in. w.c. per 100 ft
  3. 0.20 in. w.c. per 100 ft
  4. 2.00 in. w.c. per 100 ft
Show answer & explanation

0.20 in. w.c. per 100 ft

Friction rate = available static pressure × 100 / total effective length = 0.30 × 100 / 150 = 0.20.

ACCA Manual D — residential duct design

6 / Controls and wiring diagrams

On a conventional 24 VAC thermostat diagram, what does terminal C normally identify?

  1. The equipment grounding conductor
  2. The compressor demand output
  3. The heating call output
  4. The transformer secondary common
Show answer & explanation

The transformer secondary common

C is the low-voltage common side of the control transformer. It is not interchangeable with the equipment grounding conductor.

Manufacturer data (typical) — use the equipment-specific service instructions

7 / Controls and wiring diagrams

A thermostat cable is being replaced, but its wire colors do not match conventional terminal colors. What should determine the connections?

  1. Insulation color alone
  2. Documented terminal functions and the equipment wiring diagram
  3. The order of wires in the old cable jacket
  4. The physical order of terminals on a different brand of equipment
Show answer & explanation

Documented terminal functions and the equipment wiring diagram

Color is a convenience, not proof of function. Identify both ends and connect according to actual terminal assignments.

Manufacturer data (typical) — use the equipment-specific service instructions

8 / Heating systems

What is the role of the draft inducer in a typical induced-draft gas furnace?

  1. Circulate room air through the supply registers
  2. Regulate gas manifold pressure
  3. Meter the combustion gas according to room temperature
  4. Move combustion products through the heat exchanger and vent path
Show answer & explanation

Move combustion products through the heat exchanger and vent path

The inducer establishes combustion-side flow. The circulating blower is a separate device that moves indoor air across the exchanger.

ASHRAE Handbook—HVAC Systems and Equipment — heating equipment

9 / Load and psychrometrics

Which air property is directly measured by an ordinary dry-bulb thermometer shielded from radiant effects?

  1. Humidity ratio
  2. Dry-bulb temperature
  3. Dew-point temperature
  4. Specific enthalpy
Show answer & explanation

Dry-bulb temperature

A dry-bulb thermometer measures air temperature without a wetted wick. Other psychrometric properties require additional information.

ASHRAE Fundamentals — psychrometrics

10 / Refrigerant piping and charging

Why is a repaired refrigerant circuit evacuated before charging?

  1. To establish the final charge amount without a scale
  2. To replace the required pressure leak test
  3. To remove air and moisture to the specified dehydration level
  4. To remove all compressor oil from the circuit
Show answer & explanation

To remove air and moisture to the specified dehydration level

Evacuation removes noncondensables and moisture after appropriate leak testing. It does not prove every joint leak-free or establish the refrigerant charge.

ASHRAE Handbook—Refrigeration — refrigerant control devices and system practices

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