Climate Control (HVAC / A/C)
Cold air in summer, warm in winter.
Climate Control (HVAC / A/C) covers automotive air conditioning, refrigerant systems, and cabin heating. Does not replace EPA 609 certification, which remains legally required to purchase refrigerant. Everything below is free, no login, no paywall. Work through the skill areas, drill them in Study Mode, and when you're ready, prove it with the certification exam.
Your readiness to certify
Drill all 60 concepts in Study Mode. Mark each one "Got it" once you know it cold. When every concept is cleared, you're ready for the HVA exam.
What you'll be able to do
- A/C system operation: compressor, condenser, evaporator, TXV/orifice
- Refrigerant recovery, evacuation, charging procedures
- R-134a and R-1234yf identification and handling
- Leak detection with electronic, UV dye, and pressure decay methods
- Heater core service, coolant flush procedures
- Blend door and blower motor diagnosis
- Cabin filter service
Skill areas
19 lessons, each one short enough to finish in a break. Every lesson teaches the system from the ground up, ends with a call to work, and tracks which concepts you have cleared.
Regulation
Mobile A/C work is one of the most heavily regulated jobs in the shop.
Refrigerant
Refrigerant is the working fluid of the whole system, and it is also the part of the job with legal and safety teeth.
Components
You cannot diagnose an A/C system until you can walk the refrigerant loop in your head.
Diagnostics
A/C diagnosis is pattern recognition backed by gauges.
Service
A/C service work is precision work.
Leak Detection
Refrigerant does not evaporate into thin air legally — if a system is low, it leaked, and your job is to find where.
Compressor
The compressor is the heart of the system and the most expensive component in it, so compressor diagnosis carries the highest stakes on the A/C bench.
Heater
The heating half of HVAC runs on engine coolant, not refrigerant, and it generates its own family of complaints.
Blend Doors
Blend doors are the small plastic flaps inside the HVAC case that mix hot and cold air and route it to the right vents.
Blower Motor
The blower motor moves every bit of air the HVAC system delivers.
Cabin Filter
The cabin air filter is the cheapest part in the HVAC system and one of the most neglected.
Electric Vehicle A/C
Electric and hybrid vehicles still need cold air, but the compressor that makes it is a fundamentally different animal.
Heat Pump
Heating an EV is expensive — there is no hot engine to steal warmth from, and resistive heaters drain the battery fast.
Safety
A/C service puts you next to pressurized, extremely cold, and in modern systems mildly flammable chemicals.
Automatic Climate Control
Automatic climate control (ATC) systems hold a set cabin temperature by juggling blower speed, blend doors, and compressor operation.
Windshield Defrost
Defrost is a safety system, not a comfort feature — a driver who cannot see is a hazard.
Retrofit
Refrigerant transitions leave a trail of older vehicles that need service with refrigerants that are scarce or expensive.
Emerging
Refrigerant chemistry keeps evolving as regulations chase lower environmental impact.
Documentation
The wrench work is only half of legal A/C service — the paper trail is the other half.
Studied the material? Get HVA certified.
The Climate Control (HVAC / A/C) exam turns what you just learned into a verifiable credential drivers and shops can look up. 45 questions · 60 minutes · 75% to pass · Free.
Studying on MechanicRank is free forever. There's no obligation to take the exam.
The work these lessons teach.
Real jobs from Supercanic trucks — the systems above, out in the field.
Real-world cost guides for this system.
See what customers pay for the jobs this track teaches, parts, labor hours, and state-by-state ranges from our repair cost estimator.
Standards and further reading
Primary sources behind this page. Federal safety, emissions and consumer-protection references, worth reading before you authorize any repair.
- EPA Section 609 technician certification Legally required certification for anyone servicing vehicle A/C for pay.
- EPA Motor Vehicle Air Conditioning Federal rules on refrigerant handling and recovery in vehicle A/C systems.
- ASE certification The national standard for automotive technician testing and certification.
- California Bureau of Automotive Repair Licensing, consumer complaints and shop regulation in California.