End-of-Summer AC Tune-Up Checklist Every GTA Homeowner Should Follow

Anyone living in the Greater Toronto Area knows how brutal July and August can get. By the time September rolls around, our air conditioners have basically run a non-stop marathon. From the lakeside humidity of Mississauga, Burlington, and Hamilton to the crowded suburban streets of Vaughan, Richmond Hill, and Markham, our cooling systems have been working overtime just to keep us sane.

The problem is, most of us just flip the thermostat to "off" the second the first cool autumn breeze hits. That is a mistake. Ignoring your AC right after a heavy summer of work leads to higher bills, early system breakdowns, and a furnace that has to fight through leftover dirt just to keep you warm in the winter.

A quick end-of-summer checklist is all it takes to keep your system happy, your bills low, and your home comfortable.

Why Your AC and Furnace Share a Common Destiny

Most Canadian homeowners do not realize that their heating and cooling setups are not actually separate systems. They are physically linked. Your central AC relies on the exact same blower motor, primary air filter housing, and duct network as your gas furnace.

When winter hits, your heating system takes on a massive workload. Space heating and water heating actually account for roughly 80 percent of all energy used in a typical Canadian home, with space heating alone taking up 60 percent of that slice. If your air conditioner is clogged with summer dust, your blower motor has to work twice as hard to push warm air through your house, which sends your gas and electricity bills through the roof.

If you use an air-source heat pump, this seasonal shift is even more important. A heat pump does not get a winter break. It runs in reverse, pulling heat from the cold outdoor air to warm your home. Late summer is basically the halftime show for your heat pump, making a mid-year checkup absolutely vital. Since Ontario weather can flip from a September heatwave to a freezing frost overnight, you want to make sure your system is ready for anything.

Your End-of-Summer DIY Checklist

You do not need to be a certified mechanic to handle the basics. Here are five straightforward tasks you can tackle this weekend to protect your equipment:

• Change the Air Filter: Think of the filter as your system's lungs. Over the summer, it traps everything from pet hair and pollen to fine construction dust, especially in rapidly growing areas like Scarborough, Newmarket, and Durham. A dirty filter chokes off airflow, forcing the blower motor to run hot and use way too much electricity. Swap it out now so your furnace starts the winter with clean lungs. Check it monthly, and change it every one to three months.
• Clear the Outdoor Condenser: Your outdoor unit breathes out the heat from your home. But over the summer, grass clippings, leaves, and dirt coat the metal fins. Trim back any weeds or bushes so there is at least a two-foot clear zone around the unit. Also, keep an eye out for signs of mice or wasps. As nights get colder in places like Barrie, Ottawa, and Newmarket, small critters love to crawl inside these units to nest, which can easily ruin your electrical wiring.
• Audit Your Thermostat: If your thermostat is slightly off, your AC or furnace can start "short-cycling"—turning on and off rapidly. This wastes energy and wears out your system's starting components. Check your thermostat against a simple digital thermometer to make sure it is accurate. If you are still using an old dial model in an older home in Scarborough or Waterloo, think about upgrading to an Energy Star smart thermostat to automatically trim your heating costs.
• Clean the Condensate Drain: When your AC cools your home, it pulls gallons of water out of the humid air. That moisture runs down a small PVC pipe. Over time, algae and mold can form a thick sludge inside that pipe. If it blocks up, water will spill over, potentially flooding your basement floor or ruining your furnace's circuit board. Take a look to make sure the drain pan is dry and the line is running clear.
• Spot Check the Ducts: Your duct joints expand and contract as temperatures change, which can make the seams pull apart. Look over any exposed ducts in your basement or crawlspace. If you see loose tape or dark streaks of dust near the joints, it means air is leaking out. Sealing these gaps ensures your furnace actually delivers heat to your living spaces instead of wasting it in your basement ceiling.

Leave the Heavy Lifting to the Professionals

While DIY tasks are great, you should not try to service complex electrical or refrigerant components on your own. Your AC uses high-voltage power and highly pressurized chemical refrigerants to cool your home.

In Ontario, anyone working on these systems must be licensed and registered with the Technical Standards and Safety Authority (TSSA). It is not just about keeping things safe—it is also the law.

A professional preventative visit, like the up to 17-point Maintenance Plan from Constant Home Comfort, goes deep into how your system is actually performing:

• Testing Refrigerant Levels: Technicians check your operating pressures to make sure there are no slow leaks, which can ruin your compressor and spike your electricity bills.
• Checking Capacitors and Contacts: Heat degrades the electrical capacitors that help your system start up. A technician can test these parts to make sure they do not die during the next unexpected heatwave.
• Deep Coil Cleaning: Professionals use special cleaners to safely wash away the baked-on grime that blocks heat transfer on your indoor and outdoor coils.
• Furnace Combustion and CO Safety: Because your AC and furnace share components, a technician will check your furnace’s heat exchanger for cracks and run a carbon monoxide test to make sure your home stays completely safe before the burners ignite for the winter.

Local Ontario HVAC Promotions and Rebates

Note: Rebate amounts and eligibility can change over time. For the latest incentives, visit our Promotion page.

Constant Home Comfort makes staying ahead of the weather simple and affordable across the province.

• The $59 Summer AC Maintenance Special: If you are a new client in the Greater Toronto Area, you can get a complete professional air conditioner diagnostic and a brand-new, complimentary air filter installed for just $59. The visit includes checking your coils, drain line, thermostat, refrigerant levels, and carbon monoxide safety.
• Affordable Protection Plans: Protect your equipment long-term with maintenance plans starting at just $8.99 per month plus HST. This early bird price is available for the first twelve months to anyone who buys a new furnace and signs up immediately, before adjusting to the standard rate of $9.99 per month plus HST. It includes cleaning and built-in parts-and-labour protection.
• Furnace Tune-Up Special: Get your heating system ready for the snow with a professional furnace inspection for just $9.99 plus HST, down from the regular $16.99 plus HST.
• Up to $7,500 in Heat Pump Rebates: If your old AC is on its last legs, switching to a high-efficiency cold-climate heat pump can qualify you for up to $7,500 in government and manufacturer rebates. These systems handle both summer cooling and reliable winter heating down to -30 degrees Celsius. Constant Home Comfort handles all the rebate paperwork for you and offers flexible financing, including zero-down and zero-percent interest on approved credit (O.A.C.).
• Trusted Brands and Local Experts: Choose from top-tier brands like Lennox, American Standard, Daikin, Armstrong Air, and Keeprite, with same-day installation available across the GTA.

Constant Home Comfort is a multi-year HomeStars award winner (winning Best of the Best in 2024 and Best of Awards in 2026) with a reputation for honest, high-quality work. Our local technicians are stationed in communities across Ontario, and our team provides friendly service in English, Mandarin, and Cantonese.

Do not wait for your system to struggle. Book your seasonal tune-up today by calling our 24/7 support line at 1-888-675-5907, or get in touch with your local regional office.

• Markham Main Office: 2-201 Don Park Road, Markham, ON L3R 1C2 (Sales: 905-614-2459)
• Barrie Regional Office: 49 High Street, 3rd Floor, Barrie, ON L4N 1C5 Canada
• Where We Work: Markham, Richmond Hill, Scarborough, Durham, Mississauga, Vaughan, Newmarket, Ottawa, Waterloo, London, Barrie, Hamilton, Burlington, and Kanata.