An air conditioner that runs non-stop on a 30°C Barrie day usually means one of five things: it’s undersized for the house, the filter or coil is dirty, refrigerant is low, ductwork is leaking cooled air, or the house itself is letting heat pour in. Some constant running is normal during a heat wave. Running all day every day, even on moderate days, is a sign something needs attention, and it shows up directly on your hydro bill.
Quick answer:
- Normal summer behaviour: cycles of 15 to 25 minutes, longer on very hot days
- Red flag: non-stop running on days under 27°C, or the house never reaching setpoint
- Typical cost of a struggling AC: $50 to $150 extra per month on hydro
- First things to check: filter, outdoor coil, closed vents, thermostat setting
How long should an AC run per cycle?
On a typical warm day, expect two to three cycles per hour of roughly 15 to 25 minutes each. On a 32°C humid afternoon, long stretches of continuous running are normal and even efficient, since steady operation removes more humidity.
The problem is when your AC runs flat out and the house still can’t hold 23°C, or when it’s running constantly on mild days. That’s wasted electricity, extra wear on the compressor, and a shorter equipment lifespan.
What does an overworked AC cost on Ontario hydro rates?
A typical 3-ton central AC draws around 3 to 3.5 kW while running. At Ontario’s 2026 time-of-use rates, an AC that runs an extra 5 hours a day during on-peak and mid-peak windows can add roughly $2 to $4 per day, which is $60 to $120 over a summer month, on top of normal cooling costs.
If you’re on the Ultra-Low Overnight plan, daytime cooling is even more expensive per kWh, so an AC that can’t cycle off during the afternoon hits harder. Pre-cooling the house in the morning and letting a healthy system coast through peak hours only works if the system can actually keep up.
Is a dirty filter or coil making my AC run longer?
This is the most common culprit and the cheapest fix. A clogged filter starves the system of airflow, so it moves less heat per minute and has to run longer to do the same job. The same goes for the outdoor condenser coil: cottonwood fluff, grass clippings, and dust act like a blanket around it.
Replace the filter, then gently rinse the outdoor coil with a garden hose (power off first). Many “AC runs constantly” calls we get in Barrie end right there.
Could my AC be low on refrigerant?
Yes. Refrigerant doesn’t get used up, so a low charge means a leak. Symptoms include long run times, lukewarm supply air, ice on the refrigerant lines, and a hissing outdoor unit. A leak needs a licensed technician: topping up without fixing the leak just delays the same problem and adds cost. With the 2026 refrigerant transition, repairs on older R-410A systems are also getting pricier, which changes the repair-versus-replace math on aging units.
Is my house the problem, not the AC?
Sometimes the AC is fine and the house is fighting it. Common heat sources in Simcoe County homes: sun-baked west-facing windows with no coverings, leaky or uninsulated attic ductwork, weak attic insulation, and bathroom fans or dryer vents pulling in humid outdoor air. Blackout curtains on the sun side and attic air sealing are two of the highest-payback fixes, and insulation upgrades may qualify for rebates under Ontario’s Home Renovation Savings program.
When is constant running a sizing issue?
If your AC has always struggled on hot days, even when new and clean, it may simply be undersized, especially if you’ve since finished a basement, added people, or converted an attic. The fix isn’t always a bigger unit: a properly sized variable-speed system or cold-climate heat pump can run long and low on purpose, which is efficient and quiet, instead of running flat out and losing.
FAQ
Is it bad for an AC to run all day?
Continuous running during extreme heat is fine. Continuous running as a daily pattern accelerates compressor wear and usually signals an underlying problem worth diagnosing.
What temperature should I set my AC to in Barrie in summer?
24 to 25°C when home is a good balance of comfort and cost. Every degree cooler adds roughly 3 to 5% to cooling costs.
Should I turn the AC off when I leave for work?
Set it up a few degrees rather than off. Recovering a hot, humid house at 5 p.m. during on-peak rates often costs more than holding a moderate setpoint.
Why does my AC run constantly but the house is still humid?
Likely low refrigerant, poor airflow, or duct leakage: the system is moving air without transferring enough heat. That combination deserves a service call.
How much does an AC diagnostic cost in Barrie?
Most local Barrie HVAC companies, including us, charge a diagnostic fee in the $99 to $150 range, typically credited toward the air conditioner repair.
Tired of watching the hydro meter spin?
Affordable Comfort’s technicians can tell you in one visit whether your AC needs a cleaning, a repair, or whether the house itself is the issue. We serve Barrie, Wasaga Beach, and Collingwood with same-week appointments all summer. Book at barrieheatingcooling.ca or call (705) 503-4328.
