Michigan SOS mechanic test

Heating & Air Conditioning

Heating & Air Conditioning (Automobile & Light Truck) is one of the 20 Secretary of State mechanic certification tests. Here's what the test covers, according to the state's published outline.

Topic guide · questions soon

What's on the test

Official topicWeight
Heating and engine cooling system diagnosis
  • Leak diagnosis
  • Freeze protection
  • Low heater output
  • Pressurized systems
  • Defrost operation
  • Overheating
21%
General knowledge of A/C components and their functions
  • Receiver drier / accumulator
  • Temperature sensors
  • Refrigerant oil
  • Compressor clutch
  • Condenser
  • Evaporator
  • Orifice tube
  • Thermostatic expansion valve
19%
General knowledge of A/C systems
  • Refrigerant types
  • Refrigerant states
  • Operating pressures
12%
A/C diagnosis
  • Condensation
  • Leak detection
  • Overcharged / undercharged system
  • Compressor clutch
  • Gauge set readings
  • Lack of cold air
  • Electrical schematic interpretation
  • Air delivery
26%
A/C repair procedures
  • Recovering refrigerant
  • Seal replacement
  • Compressor replacement
  • Charging the system
  • Component replacement
18%
Refrigerant recovery, recycling and handling
  • Refrigerant environmental concerns
  • Recycling or recovering refrigerant
4%

Source: SOS Mechanic Testing Categories Overview (PDF). Test format: most SOS mechanic tests have 55 questions, and a few have 65–100 (SOS FAQ). Passing scores vary by test; your result letter shows the passing score and your score.

Practice questions coming soon

The Heating & Air Conditioning practice bank is being written to the official outline below. The All-Mechanic pass will include it when it launches.

Banks available now: Engine Repair · Front End, Suspension & Steering · Brakes & Braking Systems · Electrical Systems · Engine Tune-Up & Performance

Test-day facts

Source: michigan.gov/sos mechanic testing

Heating & Air Conditioning test FAQ

How many questions are on the Michigan Heating & Air Conditioning test?

The Secretary of State says most mechanic tests have 55 questions and a few have 65 to 100. The test is “quick pass,” so it ends as soon as you reach the minimum passing score.

What topics are on the Heating & Air Conditioning test?

The SOS Mechanic Testing Categories Overview lists: Heating and engine cooling system diagnosis (21%), General knowledge of A/C components and their functions (19%), General knowledge of A/C systems (12%), A/C diagnosis (26%), A/C repair procedures (18%), Refrigerant recovery, recycling and handling (4%).

How much does the test cost, and where do I take it?

Each mechanic test costs $18 (effective July 1, 2026). Tests are taken on a touch-screen kiosk at any Secretary of State office; pre-register and schedule through SOS Online Services. Approved automotive schools can also test their students.

Are these the real test questions?

No. MI Trade Prep questions are original practice items written to the official topic outline. They are not actual exam questions, and MI Trade Prep is not affiliated with the Michigan Department of State.

Sources: SOS mechanic testing · SOS mechanics page · SOS mechanic FAQ