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The Last Mile to Your 313D Residential Air Conditioning Systems Mechanic Certificate of Qualification

C of Q exam prep for the residential A/C and heat pump trade, plus the ODP card, manufacturer dealer programs, geo-exchange / IGSHPA certification, and the 313D → 313A upgrade route.

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OntarioUpdated 3 May 202613 minute read313D

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Who This Guide Is For

You're an apprentice in Ontario's 313D — Residential Air Conditioning Systems Mechanic trade. You install central A/C condensers, evaporator coils, and line sets in homes, swap aging A/C units for new heat pumps, commission residential mini-splits and multi-splits, install ground-source / geo-exchange systems, and run service calls on residential cooling and heating. You've put in your hours, you've finished (or you're in) Level 2, and the Certificate of Qualification exam is the last thing standing between you and journeyperson status.

This guide walks you through the last mile. 313D is a compulsory Ontario sub-trade. Unlike its parent trade 313A, 313D is not a Red Seal trade — it's provincial-only, scoped to residential.

One note up front. Phone STO at 647-847-3000 when a fact has a "verify before you act" caveat.

Where You Are in the Journey

A 313D apprenticeship in Ontario is 4,500 hours total:

4,020 hours of work-based training under a Registered Training Agreement (RTA) with a sponsor employer
480 hours of in-school technical training across two levels

Standard pace is two and a half years.

The 313D Apprenticeship Training Standard was updated December 4, 2023 — verify which curriculum applies to your eligibility.

You're at the last mile if:

You've finished both school levels (or you're enrolled in your final one)
You've logged 3,200+ on-the-job hours
Your sponsor has been signing off on competencies in your logbook

313D Scope: What You're Qualified to Do (and What You Aren't)

Your 313D C of Q legally authorizes you to plan, install, start up, maintain, service, repair, test, verify, commission, and decommission residential air conditioning systems, components, and accessories — including geo-exchange (ground-source heat pump) systems.

Where 313D differs from 313A:

313D is residential-only. Commercial chillers, supermarket racks, walk-in coolers, ammonia plants, industrial process cooling — all 313A scope.
313D's smaller scope means a shorter apprenticeship (4,500 hours vs 9,000) and a faster path to journeyperson.

If your career path is residential cooling and heat pumps, 313D is the right credential. If you eventually want to expand into commercial chillers or industrial refrigeration, you'll need to upgrade to 313A — covered in Step 11: 313D → 313A Upgrade Path.

Step 1: Close Out Your Hours and Logbook

The 313D Apprenticeship Training Standard (Dec 4, 2023) is the official competency list. The 313D Exam Counselling Sheet is STO's blueprint of what gets tested. Download both before serious prep.

Common gaps that hold 313D apprentices up:

Sponsor signed master units but missed sub-skills
Specific exposure missing — geo-exchange / ground-source heat pump work, mini-split / multi-split system commissioning, retrofit of older R-22 systems to current refrigerants
ODP card (refrigerant handling) hours undocumented
Hours from a previous employer never made it to STO when you switched sponsors

How to close gaps:

For missing competencies: Talk to your sponsor about exposure
For lost paperwork: Phone STO at 647-847-3000
For a vanished sponsor: STO has a process for confirming hours when the original employer is unreachable

Push for sign-offs the same week the work is done. Residential HVAC shops change ownership fast.

Step 2: Confirm Eligibility with Skilled Trades Ontario

Sponsor + TDA submit final confirmation; STO issues an eligibility notice in 4–8 weeks.

What triggers eligibility: both school levels complete and passed, 4,020 OJT hours logged, all competencies signed off, sponsor's final attestation submitted.

Step 3: Book the C of Q Exam — The Actual Portal Flow

The portal: https://portal.skilledtradesontario.ca/, authenticated through My Ontario Account.

Click-by-click:

Sign in to the STO Trades Portal
Pay the exam fee first ($150 + HST = $169.50)
Click Examination at the top of the portal
Enter your STO ID number
Select your name and exam type
Indicate accommodation needs (phone STO directly to arrange)
Choose date, time, and test centre
Add to cart, review, confirm

The first-attempt fee waiver: Apprentices completing programs on or after January 1, 2025 get the first-attempt fee waived automatically.

STO test centres: Same 22-centre network used across all trades.

Reschedule: Once at no cost with at least 5 business days' notice.

Don't book before you're ready. Rewrite costs $169.50 plus a mandatory 30-day wait.

Step 4: The Exam — Format and Blueprint

The 313D C of Q exam is a written, computer-based, multiple-choice exam.

Format (per STO's June 2023 Exam Preparation Guide):

90–150 multiple-choice questions (4 options each)
Up to 4 hours
Pass mark: 70%
The test centre supplies all materials — calculator, scratch paper, on-screen reference excerpts. Personal calculators, code books, and reference texts are NOT permitted.
Confirm exact question count and time on the 313D Exam Counselling Sheet and your Authorization to Test letter

Reference codes that matter most:

CSA B52 — Mechanical Refrigeration Code (residential AC and heat pump applications)
OBC Part 9 (Housing and Small Buildings, in force as OBC 2024)
CSA C448 — Geo-exchange systems (if you do ground-source heat pumps)
CSA F326 — Residential mechanical ventilation
OHSA Construction Projects Regulation O. Reg. 213/91
Ontario Reg. 463/10 — Refrigerants

Step 5: How to Actually Prepare

Free or near-free

Your apprenticeship in-school binders and textbooks
The 313D ATS (Dec 4, 2023)
The 313D Exam Counselling Sheet — STO's blueprint
HRAI training catalogue: hrai.ca/hrai-training-courses

Paid — verified courses

Mohawk College — Residential Air Conditioning Systems Mechanic 313D: mohawkcollege.ca/programs/skilled-trades/residential-air-conditioning-systems-mechanic-313d — Mohawk delivers in-school as 16 weeks online theory + 4 weeks in-person practical per level
St. Lawrence College (Kingston) — 313D Apprenticeship: stlawrencecollege.ca/programs/residential-air-conditioning-systems-mechanic-apprenticeship/apprenticeship/kingston
Skilled Trades Academy — 313D / G1 / G2 / G3: getatrade.com/courses/
Conestoga, Centennial — phone the registrar to confirm 313D delivery

Where 313D apprentices actually fail

Refrigeration cycle thermodynamics — pressure-enthalpy diagrams, superheat/subcool, charge calculations
Electrical/controls for residential equipment — capacitors, single-phase motor starts, control wiring, condensing unit troubleshooting
CSA B52 navigation — refrigerant classifications, charge limits for residential systems
Heat pump fundamentals — defrost cycles, reversing valves, balance points, supplemental heat sizing
Geo-exchange (ground-source) systems — loop fundamentals, pump sizing, antifreeze fluid management

Study tactics that work

Drill CSA B52 — refrigerant classifications, residential charge limits
Practice the math — refrigeration cycle calculations, electrical Ohm's law, single-phase motor circuits
Take timed practice exams
Study heat pump theory cold — Ontario's heat pump market is exploding and the exam reflects it

How long to study: Most 313D apprentices spend 2–4 weeks of focused review (10–15 hours/week) — narrower scope than 313A.

Step 6: Exam Day

Same logistics as the broader STO C of Q process: photo ID, Authorization to Test letter, no personal calculators or reference materials. Pass/fail on screen immediately. 30-day mandatory wait + $169.50 fee on rewrite.

Step 7: After You Pass

What you'll receive (4–8 weeks after passing):

Certificate of Qualification (313D) — physical certificate mailed to your address on file
Apprenticeship Completion Certificate

No Red Seal for 313D. Unlike 313A (Red Seal), 313D is provincial-only. Other provinces have their own residential HVAC credentials — talk to that province's apprenticeship authority if you plan to relocate.

What changes immediately:

You're legally allowed to work as an unsupervised residential AC mechanic in Ontario
Your wage rate jumps to journeyperson scale
You can sponsor 313D apprentices yourself (with employer approval)
You should already hold an ODP card — if you don't, get one immediately
You can write the TSSA G3 gas technician exam if you don't already hold it
You have the option to upgrade to 313A for commercial/industrial work

Step 8: The ODP Card (Mandatory)

Same as for 313A — under Ontario Regulation 463/10, anyone handling refrigerants must hold the Certificate to Handle Refrigerants issued by HRAI.

1-day approved course, 75% pass mark, valid 5 years
HRAI ODP/ODS course: hrai.ca/odp-ods-online-program
HRAI renewal: hrai.ca/odp-card-renewal
A2L / Low GWP refrigerant awareness training is increasingly required as residential AC moves to A2L refrigerants — HRAI offers it: hrai.ca/flammable-online-course

Step 9: TSSA Gas Technician Ladder

Most successful 313D journeypersons hold a TSSA G2 by Year 2. Residential furnace install, water heater service, and gas-fired equipment all require G2 to work unsupervised.

Cert	Scope
G3	Entry. Gas equipment ≤ 400,000 BTU/h. Must work under G2/G1 supervision.
G2	Independent on equipment ≤ 400,000 BTU/h (covers virtually all residential gas appliances).
G1	No BTU cap.

Apply through: TSSA Client Portal. Exam fee $225 per level, 75% pass mark, 80% class attendance.

A 313D + ODP card + G2 is the standard ticket stack for residential HVAC service.

Step 10: Specialty Paths That Pay

Heat pumps — Ontario residential decarbonization is driving rapid heat pump growth. Manufacturer training (Mitsubishi, Daikin, LG, Carrier) plus HRAI heat pump training open premium retrofit work — and rebate programs typically require certified installers.
Geo-exchange / ground-source — CSA C448-certified installers are in chronic demand for premium residential and small commercial ground-source heat pump installations
Smart thermostats and home automation — integration with Nest, Ecobee, Honeywell systems
HRV / ERV (residential ventilation) — pairs well with sheet metal scope; CSA F326 specialty
Building Performance Institute (BPI) auditor certification — opens premium retrofit and audit work for energy-efficiency rebate programs

Step 11: 313D → 313A Upgrade Path

If your career goal is commercial chillers, supermarket refrigeration, ammonia industrial, or large institutional work, you'll need to upgrade to 313A.

There's no automatic conversion. STO treats 313A as a separate trade with its own training standard and exam.

The documented routes:

Trade Equivalency Assessment (TEA)

Apply through STO at skilledtradesontario.ca/experienced-workers/trade-equivalency-assessment/
$90 application fee
STO evaluates whether your 313D experience plus any commercial/industrial exposure is sufficient to challenge the 313A C of Q exam directly
Minimum 8-week assessment timeline

Re-apprentice as 313A

Register a new RTA as a 313A apprentice with a sponsor doing commercial/industrial work
Some hours from your 313D apprenticeship may credit toward the 313A 9,000-hour requirement (STO assesses case by case)
Practical experience reports suggest "1 or 2 terms left of schooling" plus topping up to 9,000 hours OJT — a formal hour-conversion table is not publicly published by STO. Phone STO at 647-847-3000 to confirm what credit applies to your specific work history.

Continuing Competency

ODP card renewal every 5 years
TSSA gas certificate renewal
A2L / Low GWP refrigerant training — increasingly required
Heat pump and geo-exchange continuing education through HRAI and manufacturers
CSA B52 code update training

The Union Pathway (UA Local 787)

Same as 313A — UA Local 787 covers RAC mechanics province-wide, with JTAC-787 as the training centre at 905-790-9662.

UA Local 787 HQ: 419 Deerhurst Drive, Brampton L6T 5K3 / 905-790-1019.

The residential market skews more heavily non-union than 313A's commercial scope, but Local 787 represents both. For non-union 313D apprentices: You can join Local 787 after qualifying — initiation fee and dues apply.

Provincial and Federal Incentives — Verified May 2026

Active in 2026:

Ontario Tools Grant: $600 for construction trades (313D qualifies)
Ontario Apprenticeship Completion Bonus: $2,000 for non-Red-Seal trades within 180 days of receiving your Certificate of Apprenticeship. 313D is not Red Seal, so this bonus DOES apply. Verify with STO before applying.
Federal Tradesperson's Tools Deduction — up to $1,000 federal deduction at tax time, 2026 base $1,501
Achievement Incentive Program (employer-side) — up to $17,000 per apprentice

No longer claimable / Red Seal only (313D doesn't qualify):

Federal Apprenticeship Completion Grant ($2,000) — CLOSED March 31, 2025. Replaced by Team Canada Strong (not yet active as of May 2026).
Canada Apprentice Loan — Red Seal trades only
Apprenticeship Job Creation Tax Credit — Red Seal only

Provincial summary: ontario.ca/page/financial-supports-apprentices-and-sponsors.

Common Mistakes to Avoid

Booking the exam before you're ready. First attempt is fee-waived for apprentices completing on/after Jan 1, 2025; rewrite costs $169.50 plus a 30-day mandatory wait.
Letting your ODP card lapse. Mandatory under O. Reg. 463/10.
Letting your logbook fall behind. Residential HVAC shops change ownership fast.
Underestimating CSA B52 — refrigeration code is heavily tested.
Skipping electrical/controls — consistently a high-failure area.
Cramming. A week covers about 10% of what's tested.
Treating the C of Q as the finish line. ODP card, TSSA G2, A2L training, manufacturer specialty certifications — those open the higher-margin work.
Not adding TSSA G2. A 313D without G2 is locked out of any gas-fitting work.
Underestimating heat pump growth. Ontario residential decarbonization is creating sustained demand for certified heat pump installers.
Missing the $2,000 Ontario Apprenticeship Completion Bonus. Non-Red-Seal trades qualify; apply within 180 days of your Certificate of Apprenticeship.

What This Costs (Summary, May 2026)

Item	Cost
C of Q exam fee (first attempt, post-Jan 1 2025 completers)	$0 — fee waived
C of Q exam fee (rewrite)	$150 + HST = $169.50
Practice exams / online prep	$100–$300
College C of Q prep (Mohawk, St. Lawrence)	$300–$700
ODP card initial course (HRAI)	$200–$400
ODP card renewal (every 5 years)	$100–$200
HRAI A2L / Low GWP course	$150–$300
TSSA G2 training and exam	$1,500–$2,500
HRAI heat pump training	$300–$600
Manufacturer specialty certifications	typically employer-paid
Estimated minimum to certify	~$300 (rewrite-fee allowance + ODP)
Typical with paid prep	~$700–$1,200
Full setup with G2 + ODP + heat pump training	~$3,500–$5,000 in your first journeyperson year

Apply against the Ontario Apprenticeship Completion Bonus ($2,000 — 313D qualifies as non-Red-Seal), the Ontario Tools Grant ($600), and the Tradesperson's Tools Deduction (federal).

What Happens Next

You have your 313D. You're a journeyperson residential air conditioning systems mechanic. The most common next steps:

Stay employed at a residential HVAC contractor. Build experience, save money, stack tickets.
Add your ODP card (mandatory)
Add TSSA G2 within Year 1 — mandatory for any gas-fitting work
Add HRAI heat pump training and A2L training — premium specialty work
Add manufacturer-specific heat pump certifications (Mitsubishi, Daikin, LG, Carrier) for rebate-program-eligible installations
Go independent. Residential HVAC is one of the lowest-barrier paths to self-employment in Ontario mechanical trades
Upgrade to 313A if you want commercial chillers or industrial refrigeration