Fast facts
| Trade code | 313D |
|---|---|
| Sector | Construction |
| Classification | Compulsory trade (O. Reg. 876/21, s. 2) |
| Certifying exam | Required (O. Reg. 876/21, s. 3) |
| Apprentice to journeyperson ratio | Subject to a ratio (O. Reg. 876/21, s. 4) |
| Red Seal trade | No |
| Active apprentices in Ontario | 350 (reported in Ontario's apprenticeship dataset) |
| Approved sponsors | 251 |
| Certifying body | Skilled Trades Ontario |
Last verified August 20, 2026 against the sources listed below.
What does a residential air conditioning systems mechanic do?
A Residential Air Conditioning Systems Mechanic works on residential air conditioning systems including geo-exchange systems.
Skilled Trades Ontario describes the work of this trade as follows:
- plans, lays out, installs, starts-up, connects, maintains, services, repairs, tests, verifies, commissions, and decommissions residential air conditioning systems, components and their accessories
- installs and connects piping for the purpose of conveying all types of refrigerants used for both primary and secondary heating and cooling
- maintains, services, repairs and replaces system components and accessories, including electrical and electronic components
- measures, cuts, bends, threads and connects pipe to functional components and utilities
- services, tests, adjusts, commissions and decommissions the system
How long is the residential air conditioning systems mechanic apprenticeship?
| Total training hours | 4,500 |
|---|---|
| On the job | 4,020 hours |
| In school | 480 hours |
| In-school levels | 2 |
These hours are set by the Registrar of Skilled Trades Ontario under section 14 of the Building Opportunities in the Skilled Trades Act, 2021.
What do you study in school for the 313D?
The in-school portion covers, but is not limited to:
- workplace health and safety
- applied trade mathematics
- engineering drawings and documentation
- trade practices
- mechanical cooling cycle fundamentals, components and accessories
- electrical and electronic fundamentals
- pipe joining, welding, brazing and soldering
- installation and system start-up procedures
- applied psychometrics
- pints and heat load calculations
- air distribution systems and accessories
- electrical and electronic control systems
- rigging and hoisting
- commissioning
Is residential air conditioning systems mechanic a compulsory trade in Ontario?
Yes. Residential Air Conditioning Systems Mechanic is one of the 23 trades classified as compulsory by section 2 of O. Reg. 876/21 under the Building Opportunities in the Skilled Trades Act, 2021. To practice a compulsory trade legally in Ontario, a person must hold a Certificate of Qualification, a Provisional Certificate of Qualification, or a Registered Training Agreement, and their information appears on the Skilled Trades Ontario Public Register, where anyone can check whether a specific person is certified.
Working in this trade without one of those three documents is an offence, subject to limited exemptions such as approved pre-apprenticeship program participants. See the full list of compulsory trades in Ontario for how this trade compares to the other 22.
How do you become a residential air conditioning systems mechanic in Ontario?
The apprenticeship pathway for this trade is administered by Skilled Trades Ontario under section 14 of the Building Opportunities in the Skilled Trades Act, 2021:
- Find a sponsor and register a training agreement. An employer or union sponsor takes you on and the training agreement is registered with the ministry. For this trade the Registered Training Agreement is also your legal authorization to work while you train.
- Complete the on the job and in school training. The skills are set out in the trade's Apprenticeship Training Standard, signed off by your sponsor as you demonstrate them, alongside levels of in school theory at a training delivery agent.
- Receive your Certificate of Apprenticeship. Skilled Trades Ontario issues it when the program is complete.
- Pass the certifying exam. This trade has a certifying exam under O. Reg. 876/21, s. 3. Passing it earns the Certificate of Qualification, which compulsory trade workers must then hold and renew to keep practicing.
The exact training standard, current curriculum and program details are on the Skilled Trades Ontario page for Residential Air Conditioning Systems Mechanic. On the job hour requirements vary by trade and are not published on this page yet; confirm them in the training standard before signing an agreement.
Is there an apprentice to journeyperson ratio for the 313D?
Yes. Residential Air Conditioning Systems Mechanic is one of the 33 trades that section 4 of O. Reg. 876/21 makes subject to an apprentice to journeyperson ratio. The regulation establishes that a ratio applies, but the numeric ratio itself is not stated in section 4. Confirm the current ratio with Skilled Trades Ontario before registering an additional apprentice, because it limits how many apprentices a sponsor may train at once.
Is the 313D a Red Seal trade?
No. Residential Air Conditioning Systems Mechanic is an Ontario prescribed trade but is not part of the Interprovincial Red Seal Program, so an Ontario credential in this trade does not carry automatic recognition in other provinces. Workers moving to another province should check that province's own trade classification.
How often does the certificate need to be renewed?
Journeypersons in compulsory trades must renew their Certificate of Qualification every year, per Skilled Trades Ontario. A lapsed certificate in a compulsory trade means the holder is no longer legally entitled to practice the trade until it is restored, so the renewal date is worth tracking ahead of time. The current renewal fee is not published on this page yet; confirm it with Skilled Trades Ontario.
Already experienced? The Trade Equivalency Assessment
Workers with experience from outside Ontario's apprenticeship system, or from another country, can apply for a Trade Equivalency Assessment instead of starting an apprenticeship. Approval requires verifiable evidence of competency in the trade's Training Standard and experience at least equal to the trade's total training time; if approved, you challenge the certifying exam directly. The assessment costs $235 plus HST, and a reassessment with new evidence costs $100 plus HST, per Skilled Trades Ontario's Trade Equivalency Assessment page.
Certification is not the only paperwork
A Certificate of Qualification covers the person. Running a business in the trade carries its own obligations: many Ontario municipalities require a contractor licence on top of personal certification, and construction employers must complete WSIB registration before work begins. Both are indexed on our sister site: municipal contractor licensing requirements by city and WSIB Form 1000, registration of constructors and employers, on Ontario Trade Registry.
Where can you train as a residential air conditioning systems mechanic in Ontario?
| Public training providers | 7 colleges deliver the in-school portion |
|---|---|
| Approved sponsors | 251 employers registered to train apprentices |
| Apprentices in training | 350 |
Counts are from Ontario's published apprenticeships dataset. A sponsor is the employer or union that registers and trains the apprentice; you need one before an apprenticeship can start.
How dangerous is construction work in Ontario?
Ontario does not publish injury figures per trade, only by sector. In 2024 the Ministry of Labour recorded 18 worker fatalities and 442 critical injuries under the construction health and safety program. See the ten-year counts and what they leave out.
Related Ontario trades
Other construction sector trades with certification records on this registry:
Official verification sources
- RegulationO. Reg. 876/21, Prescribed Trades and Related Matters (e-Laws)
- Certifying bodySkilled Trades Ontario: Residential Air Conditioning Systems Mechanic
- ActBuilding Opportunities in the Skilled Trades Act, 2021 (e-Laws)
- Participation dataOntario open data: Apprenticeships dataset
Classification, exam requirement and ratio status on this page are read directly from O. Reg. 876/21 as consolidated on e-Laws, not from secondary summaries. Facts not yet verified against a primary source are marked as not published rather than estimated.