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C-20 License: Guide for HVAC Contractors

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The C-20 License is one of the most important licenses offered by the state of California.

As the planet gets hotter and more parts of the world reach higher temperatures during the summer months, HVAC professionals will continue to be in higher demand. 

This article will provide you with every single detail you need to know about the C-20 HVAC License in California!

What Is a C-20 HVAC license?

two men with hard hats looking at blueprint plans assessing an HVAC

A warm-air heating, ventilating and air-conditioning contractor fabricates, installs, maintains, services and repairs warm-air heating systems and water heating heat pumps, complete with warm-air appliances; ventilating systems complete with blowers and plenum chambers; air-conditioning systems complete with air-conditioning unit; and the ducts, registers, flues, humidity and thermostatic controls and air filters in connection with any of these systems. This classification shall include warm-air heating, ventilating and air-conditioning systems which utilize solar energy.CSLB.GOV

The HVAC License is required for all contractors looking to bid on residential and commercial heating ventilation or air conditioning projects where the cost of labor and materials exceeds $500. 

The C-20 HVAC License is what is considered a prime license.

This means that the CSLB considers it one of the most important licenses when it comes to protecting the public. 

Heating ventilation and air conditioning are services that most of the consumer public depends on, so naturally, there is more oversight for HVAC contractors.

Online Practice Exams and Study Guides

Duties of an HVAC Contractor

HVAC Contractors engage in a wide variety of duties including:

  • Installing and maintaining A/C and heating units
  • Changing Freon
  • Fabrication and servicing of A/C, solar energy, and heating units
  •  Installing plumbing hooks, electrical hook ups, and thermostats
  • Bidding, Accounting, Preparing invoices and estimates
  • Maintaining a safe job site

To obtain the C-20 license, you will be tested on all aspects of HVAC installation, repair, and maintenance.

It will be essential to your success to become familiar with all the areas of expertise that fall under the HVAC trade.

An HVAC contractor that holds the C-20 license is legally is not allowed to bid on a project that falls outside of the spectrum of installation, repair, or maintenance of heating, ventilation, and air conditioning systems.

C-20 License and the General Contractor

Two large commercial AC units outside of a home

Typically, an HVAC Contractor works directly with a homeowner or property management company to fix and repair heating systems, thermostatic controls, air conditioning units, etc.

HVAC Contractors may also work with General Contractors who are completing a remodel or construction project for a client. 

General Contractors oversee that the Heating, Ventilation, and Air Conditioning side of the construction process is executed up to code and to environmental standards.


The Contractors State License Board (CSLB) is the governing body for all contractors in the state of California. 

Their sole responsibility is to protect the consumer public and ensure that anyone charging over $500 for construction services is qualified and registered with the state of California. 

The C-20 License is issued to HVAC contractors by the CSLB.

The CSLB administers applications, exams, and maintains a database of all active and inactive contractor license numbers which are public domain.

How to get your C-20 License

To get a C-20 license in California, you must prove a minimum of 4 years of journeyman level experience and pass a two-part state exam with the Contractor State License Board.

To qualify for an exam date you must meet the following requirements:

  • Be at least 18 years of age
  • Have a valid Driver's License or USA Issued Identification
  • Have a Social Security or ITIN #
  • Not Currently be on probation or parole

You must also have:

  • 4 Years Journey Level Experience
  • A Qualifying Individual to sign off on your experience
  • A way to prove your experience if the state asks for documentation

What is Journey Level Experience?

hvac contractor checking an AC unit

Journeyman level experience means that you have worked unsupervised full time for an HVAC company, or for a contractor that holds the C-20 License.

  • A journeyman HVAC contractor can perform all of the duties associated with his or her trade.

The CSLB will want to see four full-time years over the last ten years. The years do not need to be consecutive, but they do need to be four years in total. 

Recommended Resources

Signature of a Qualifying Individual

The following people may be used as Qualifying Individuals to sign off on your experience when applying for the C-20 license:

  • Licensed General Contractor
  • C-20 License Holder
  • Fellow Employee (within the last 10 years)
  • Former Supervisor (within the last 10 years)
  • Business Associate
  • Fellow Journeyman
  • Union Representative

Filling out the C-20 License Application

Your Qualifying Individual will also need to provide a brief but detailed description of your glazing knowledge and skillset.

The way this description is written will be critical to whether or not your application is accepted. For example:

“Ed is a nice guy and has worked in HVAC…” is not going to work

The CSLB will want to see something more like: 

Ed has installed and repaired A/C Units, changed freon, tested components to determine necessary repairs” etc

Work Experience for the C-20 License

copper plumbing tubing and HVAC vents being installed.

You must be prepared to submit documentation supporting the experience you claim to have. The Contractors State License Board gives you a few ways that you can prove your experience.

  • Tax Returns
  • Check Stubs
  • Contracts
  • Material Order Invoices or Receipts

The CSLB  receives thousands of applications per month so there is a good chance they won’t document your experience but if you are one of the applicants that get reviewed you will need to be ready to submit something. 

The CSLB does not accept pictures of projects.

Application Processing, Fees and Criminal History

The time it takes to get your application processed and assigned a test date fluctuates throughout the year.

Typically you can expect:

  • 6-8 Week Application Processing Time
  • 3-4 Week wait for an Exam date

I have seen situations where applicants got their test date sooner and somewhere they got their test date much later.

The most common reasons your application would get held up are:

  1. Time of year (processing time slows down during the holidays) 
  2. Criminal History 
  3. Proving Experience
  4. Mistakes on your application 

Application Costs for the C-20 License 

The Current CSLB fees are: 

Can you get a Contractors License with a Felony in California?

Man wearing handcuffs. live scan fingerprinting is required of anyone looking to get the C-20 License

Having a criminal record in no way stops you from getting a C-20 License. I have personally helped guys with all types of criminal records obtain multiple licenses.

The key is, to be honest on the application, even if the felony or misdemeanor happened years ago and even if it was expunged.

BE 100% HONEST ON THE APPLICATION, because they will see everything anyway when you do fingerprinting.

The CSLB handles criminal records on a case-by-case basis. Remember, their responsibility is to protect the public.

In my experience, they are primarily concerned with criminal charges associated with Fraud, Embezzlement, or Forgery.

C-20 HVAC License Exam

The C-20 license exam will consist of:

  • 115 Questions of Contractor LAW
  • 115 Questions on HVAC
  • 3 hours to complete each portion
  • Multiple choice exam done on a computer
  • Closed Book

Content of the TRADE Examination

The C-20 HVAC License Examination is broken up into 4 parts:

1. Evaluation, Design, and Estimation (26%)

  • HVAC system design and evaluation
  • Load and psychrometric calculations
  • Duct system design and layout
  • Job cost estimation

2. Fabrication, Installation, and Startup (27%)

  • Duct system fabrication
  • Equipment installation
  • Electrical and mechanical components
  • Plumbing and refrigeration components
  • Air distribution and duct systems
  • HVAC system startup

3. Troubleshooting, Repair, and Maintenance (22%)

  • HVAC system diagnostic tests and evaluation
  • HVAC system maintenance or repair

4. Safety (25%)

  • Personal protective equipment (PPE)
  • Job site safety requirements (Cal/OSHA)
  • Handling hazardous materials

CSLB Test Locations

logo of the Contractors State License Board, illustration of a paint brush, saw and cement truck

  • Berkeley
  • Fresno
  • Norwalk
  • San Jose
  • Oxnard
  • Sacramento
  • San Bernardino
  • San Diego

C-20 License Study Guides and Exam Prep

featured image for a blog post about choosing a contractor license school. The C-20 license will require you to pass a two part exam

Some things to remember:

  • The questions you will see on the exam may use outdated terms
  • Processes may be completely different from how things are done on the job site
  • You will see questions about things you may have never done before
  • Questions will be presented to you as if you are running a large scale construction business with several employees and jobs happening all at once. 
  • Know all aspects of your trade

Remember, they are testing you on all the things you will be allowed to bid on, so make sure that you are knowledgeable on all aspects of your trade.

Studying C-20 license practice tests along with explanations and diagrams can help you a lot.

Learn more about Contractor License Schools.

Be as prepared as you possibly can. Studying just 10 minutes a day consistently can dramatically increase your chances of passing the test on your first try.

Focus on and study ONLY the information that you need to pass the C-20 License exam

HVAC Apprenticeship

instructor teaching an apprenticeship how to service an AC unit

An apprenticeship is an excellent way to build a solid foundation for a career as an HVAC contractor

If you don’t have the four years required journeyman level experience to obtain a C-20 license, not to worry.!

Your journey begins here 

HVAC work is highly specialized with an unlimited amount of opportunity.

Whether you are brand new to the HVAC Trade or already have a little bit of experience there are options for you.

Generally, someone looking to get into the industry would want to look into an apprenticeship or certification program.

Blueprint Reading Course

featured image for a blog post about how to read blueprints, which is a vital skill for anyone applying for the C-20 license

It is critical for the HVAC contractor to be able to follow specific designs and blueprints to:

  • Install and repair HVAC Systems
  • Locate Air ducts
  • Safely connect systems to fuel and water supply lines

The ability to quickly interpret construction blueprints is an invaluable skill for all tradesmen but is especially important for HVAC contractors. Learn more about Blueprint Reading.

EPA Certification

logo of the united states environmental protection agency. HVAC contractors should know how to safely contain lead paint if it is present

Containing lead paint when making alterations to a home or structure built before 1978 is vital for HVAC contractors.

Having a solid understanding of the health effects of lead paint and containment procedures is crucial. 

The Environmental Protection Agency offers several certifications that are easy to get.

HVAC contractors looking to build a profitable business must position themselves as experts and the authority within their industry.

They must be a source of information beyond just HVAC for their clients and community if they want referrals and repeat business.

How to get an EPA certification.


Getting the C-20 License can be a huge step up in your career if you are looking to open your company or take on larger clients!

The key is to take action and follow these steps from beginning to end. You can also learn more about HVAC licensing in other states:




New Mexico





For a detailed explanation of this process of becoming a journeyman, check out my article: Apprentice vs Journeyman!

If you have found this article helpful feel free to drop a comment below and be sure to check back for updates!