Quick answer: the five AC maintenance tips that matter most
Change the filter
A clogged furnace filter is the most common cause of frozen coils and weak cooling.
Clear and rinse the outdoor unit
Grass, leaves and cottonwood fluff smother the coil and push up hydro bills.
Keep the drain flowing
A blocked condensate line can shut the AC off or leak water around the furnace.
Set the fan to Auto and the thermostat to 24–25 °C
Better humidity control and lower bills.
Book a spring tune-up ($120 – $200)
A technician tests the parts you can’t, like the capacitor and refrigerant charge.
Central air in most Ottawa homes is a split system: an outdoor condenser beside the house and an indoor coil sitting on top of the furnace, which uses the furnace blower and filter. If you have a heat pump, the same tips apply. Before any hands-on job outside, switch off the power at the disconnect box beside the unit.
Outdoor unit (tips 1–5)
1. Uncover the unit and give it room
Take off any winter cover before the first warm day, because running the AC with it on traps heat around the compressor. Trim shrubs, fences and tall grass back at least 45–60 cm on every side, and keep about 1.5 metres clear above the fan. Don’t store patio furniture or the BBQ against it.
2. Rinse the coil, gently
In June, Ottawa’s cottonwood trees shed fluff that mats onto condenser fins like felt. With the power off, rinse the fins with a garden hose from the inside out if you can reach, or straight in from outside on low pressure. Never use a pressure washer; it folds the fins flat.
3. Straighten bent fins
Hail, lawn trimmers and kids’ balls bend the thin aluminium fins and block airflow. A fin comb from a hardware store, or a butter knife used gently and no deeper than about 1 cm, will open small patches. Wear gloves, as the edges are sharp. Large crushed areas are best left to a technician.
4. Check that the pad is level
Freeze-thaw cycles and frost heave make concrete and plastic pads settle or tilt over a few winters. A slight lean is fine. If the unit tilts noticeably, vibrates, holds water underneath or pulls on the copper lines, have it re-levelled before the lines or compressor are strained.
5. Check the refrigerant line insulation
The larger copper line running into the house is wrapped in black foam insulation. Sun and squirrels break it down. Cracked or missing insulation lets the line pick up heat and sweat, which wastes cooling. UV-rated foam pipe insulation is an easy fix; don’t disturb the lines or fittings themselves.
Indoor equipment (tips 6–10)
6. Change the furnace filter on schedule
Your central AC pulls every bit of air through the furnace filter. Check it monthly in July and August and replace it when it looks grey: every 1–3 months for a 1-inch filter, longer for a 4- or 5-inch media filter. Homes with pets or renovation dust need more frequent changes. Our furnace filter guide covers MERV ratings.
7. Keep vents and returns open
Closing registers in unused rooms doesn’t save money on a central system. It raises duct pressure and can freeze the coil. Keep supply registers open and keep sofas, beds and rugs off the large return grilles.
8. Keep the condensate drain flowing
On a humid day the indoor coil pulls litres of water out of the air. It drains through a small line to a floor drain or condensate pump. Pour a cup of white vinegar into the drain line or trap each spring to slow algae, and listen for the pump cycling on hot afternoons. Water on the floor near the furnace means the drain needs attention.
9. Turn off the furnace humidifier for summer
A humidifier left running in July fights your AC by adding the moisture it is trying to remove. Close the humidifier’s bypass damper (often marked Summer/Winter), turn the humidistat to off and shut its water valve. Reverse it in the fall. See our humidifier page for how these systems work.
10. Set your dampers for summer
Many Ottawa homes have small levers on the round ducts near the furnace. Partly closing the dampers to basement registers in summer pushes more cold air upstairs, where heat collects. Mark the winter positions with tape first so you can set them back.
Thermostat and settings (tips 11–14)
11. Run the fan on Auto
With the fan set to On, the blower keeps running between cooling cycles and blows moisture from the wet coil back into the house. On Auto, water drains away and rooms feel drier at the same temperature. The exception is a short run of circulate mode to even out a hot upstairs.
12. Pick a steady setpoint and modest setbacks
24–25 °C while you’re home is comfortable for most people once humidity is under control. Raise it 2–3 °C when you’re out, rather than switching the AC off. During a heat wave, shutting it off lets heat soak into walls and furniture, and the system may not catch up before bedtime.
13. Use a programmable or smart thermostat
Scheduling does the setbacks for you, and many smart models show humidity and send filter reminders. Make sure the thermostat is compatible with your equipment, especially two-stage or variable-speed systems. Oria offers smart thermostat installation, typically $250 – $600 installed.
14. Keep heat sources away from the thermostat
Direct afternoon sun, a lamp, a TV or a kitchen nearby makes the thermostat read high, so it keeps cooling while the rest of the house is cold. If yours sits in a sunny hallway, close the blind nearby or ask about relocating it.
Home envelope (tips 15–18)
15. Close blinds on south and west windows
Sun through glass is one of the biggest heat loads in a house. Close blinds or curtains on south- and west-facing windows from late morning to early evening. Exterior shades, awnings and low-e window film work better still, because they stop heat before it reaches the glass.
16. Seal leaks and top up attic insulation
The same gaps that let in −25 °C air in January let in humid 30 °C air in July. Weatherstrip doors, caulk window trim and seal gaps where pipes and wires pass through walls. In the attic, adequate insulation and clear soffit vents stop the upstairs bedrooms from baking.
17. Use ceiling fans the right way
In summer, set ceiling fans to spin counter-clockwise so they push air down. The breeze makes a room feel a couple of degrees cooler, so you can raise the setpoint. Fans cool people, not rooms, so switch them off when you leave.
18. Cut the heat you make indoors
On hot days, cook on the BBQ, run the dryer and dishwasher in the evening, and use bathroom and kitchen exhaust fans to remove steam. Swapping old incandescent bulbs for LEDs also trims a surprising amount of heat.
When to call a pro (tips 19–21)
19. Book a spring tune-up
A professional AC tune-up costs $120 – $200 in Ottawa. The technician cleans the outdoor coil, tests the capacitor and contactor, tightens electrical connections, checks refrigerant pressures and temperature drop, and clears the drain. April and May are the easiest months to book. Our AC maintenance service explains each step.
20. Know the warning signs
Ice
Frost on the copper lines or indoor coil.
Hissing or bubbling
Usually a refrigerant leak.
Breaker trips twice
Leave it off and call.
Humming but no fan
Often a failed capacitor.
Rattling or shaking
Refrigerant work in Ontario must be done by a licensed technician, and every Oria tech holds a refrigeration licence. Most AC repairs cost $150 – $1,200.
21. Plan the replacement before it fails
Most central air conditioners last 12–15 years. If yours is in that range, runs on phased-out R-22 or needs a compressor ($1,800 – $3,500), price a new system at $4,000 – $8,000 before a July breakdown forces the choice. Ask for a load calculation rather than “same size as the old one”, and price a cold-climate heat pump too. The final price depends on the home, the equipment and the ductwork, and Oria gives free quotes on any equipment purchase. Old units hold refrigerant that must be recovered by a licensed technician, so don’t put one out with the garbage.
Ready for a tune-up or a quote? Call (613) 866-1869 or book AC maintenance in Ottawa. Oria is family-owned, has served Ottawa since 2014 and services all makes and models.
Frequently Asked Questions
How often should an air conditioner be serviced?
Once a year, ideally in April or May before the first Ottawa heat wave. A spring tune-up costs $120 to $200 and covers coil cleaning, electrical tests, refrigerant checks and the condensate drain. Between visits, change the furnace filter every one to three months and keep the outdoor unit clear of debris and cottonwood fluff.
Can I clean my AC unit myself?
Yes, the outside of it. Switch off the power at the disconnect box, clear leaves and grass, and rinse the fins gently with a garden hose. Don’t use a pressure washer, and don’t open the electrical panel or touch the refrigerant lines. Coil chemicals, electrical testing and refrigerant checks belong to a licensed technician during a tune-up.
What temperature should I set my AC to in summer?
For most Ottawa households, 24 to 25 °C while you’re home is comfortable when humidity is under control. Raise the setpoint by 2 or 3 °C when you’re out instead of turning the AC off. Running the fan on Auto rather than On also helps, because it lets the coil drain moisture between cycles.
Should I cover my outdoor AC unit in winter?
A cover isn’t required, since condensers are built to sit outside year-round. If you use one, choose a top-only cover or a breathable cover that protects from falling ice and leaves without trapping moisture. A fully wrapped plastic tarp can encourage rust and gives mice shelter. Always remove the cover before running the AC in spring.
Why is there water around my furnace when the AC runs?
Your AC pulls water from the air, which drains from the indoor coil through a line to a floor drain or condensate pump. Water on the floor usually means that line is clogged with algae, the pump has failed, or the coil froze and is melting. Clear the line with a wet/dry vacuum, check the pump, and call if it continues.
Do closed vents save money with central air?
Not usually. A central system is designed to push a set amount of air, so closing registers raises pressure in the ducts, can freeze the coil and may make the blower work harder. Keep most vents open. To shift cooling upstairs, partly close the basement dampers at the trunk line instead, and mark the winter positions first.
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