You set the thermostat. You hear the AC kick on. And yet, hours later, your home still feels like a sauna.
If your air conditioner is running nonstop but the temperature refuses to drop, you’re not alone. It’s one of the most common issues Edmonton homeowners face when summer hits full force and while it’s tempting to crank the system lower or assume it’s just “working hard,” the reality is this: something’s off.
In this blog, we’ll break down the most common reasons your air conditioner runs all day without cooling and when it’s time to book a professional air conditioner service before your next power bill spikes. If comfort’s not cutting it, this guide is for you.
How a Healthy Cooling Cycle Should Work
Central air conditioning is a closed‑loop heat‑exchange system:
- Warm return air is pulled across the indoor (evaporator) coil, where refrigerant absorbs heat.
- The refrigerant carries that heat outside to the condenser unit, releasing it into the outdoor air.
- The compressor keeps refrigerant moving while the blower redistributes cooled air through ductwork.
When any step is disrupted, the unit runs longer to hit the setpoint. Eventually, it may run continuously without ever crossing the finish line.
Why Your AC Runs Non‑Stop But The House Stays Warm
Dirty Or Clogged Air Filters Suffocate Airflow
A filter packed with dust and pet dander acts like a wool scarf on a July afternoon, throttling return airflow and forcing the system to struggle. Natural Resources Canada recommends inspecting or replacing filters at least every three months, and monthly during heavy use.
DIY check: Hold the filter up to a light bulb. If you can’t see light through most of it, replace it.
Thermostat Mistakes And Malfunctions
If the fan setting is on “On” instead of “Auto,” the blower will run around the clock, even when the compressor isn’t cooling. Mis-calibrated sensors or loose wiring can also keep the system cycling aimlessly.
Pro tip: Verify the mode is Cool, the setpoint is reasonable (around 24–25 °C), and the fan is on Auto before you assume bigger problems.
Low Refrigerant Or Hidden Leaks
Refrigerant is the lifeblood of your cooling loop. Even a small leak reduces pressure, lowers the evaporator temperature, and can eventually freeze the coil solid. The compressor then runs continuously with little or no cooling effect.
Warning: Recharging refrigerant without fixing leaks is a temporary band‑aid and, in Canada, must be done by a certified technician.
Matted Condenser Coils And Blocked Outdoor Units
The outdoor coil needs unobstructed airflow to dump heat. Grass clippings, cottonwood fluff, or stacked patio furniture can blanket the fins and trap warm air. A quick hose‑down (gentle, from inside‑out if possible) and 60 cm clearance on all sides restore performance.
Frozen Evaporator Coil
Low airflow, low refrigerant, or a failed blower motor can drop coil temperature below freezing. Ice insulates the coil from warm air, so the unit keeps running but never cools. Shut everything down, let it thaw fully, then address the root cause.
Undersized (Or Oversized) Equipment
If your builder undershot square‑footage heat‑gain calculations, the unit will chase temperature all day. Oversized systems, short‑cycle, never dehumidify properly, and leave the air clammy. A professional load calculation (Manual J or CSA F280) is the only way to confirm sizing.
Leaky Ductwork And Poor Home Insulation
In older Edmonton homes, unsealed duct joints can bleed 20 %–30 % of conditioned air into attics or crawl spaces. Likewise, minimal attic insulation means heat continually seeps back into living areas, forcing the AC to run longer.
Hidden Issues You Might Overlook
Edmonton’s Summer Humidity Overloads Cooling Capacity
A muggy 28 °C day feels warmer than a dry one because latent heat from moisture makes the body sweat less effectively. An AC sized only for dry‑bulb temperature may run indefinitely trying to wring out humidity. A whole‑home dehumidifier or variable‑speed air conditioner can solve the problem.
Return‑Air Imbalance
Closing too many interior doors or supply vents creates pressure differentials that starve the system of return air. The blower ramps up, the noise increases, but the cooling doesn’t.
Aging Electrical Components
Capacitors lose charge, contactors pit, and compressor windings break down over time. The system may still start, but efficiency plummets, and continuous runtime masks the gradual failure.
Quick Homeowner Checklist Before Booking Professional Air Conditioner Service
- Replace the air filter if it’s older than 30 days or visibly dirty.
- Check the thermostat: mode = Cool, fan = Auto, battery fresh.
- Inspect the outdoor condenser: clear debris, trim vegetation 60 cm away, rinse fins.
- Open all supply and return vents; ensure interior doors are ajar for airflow.
- Look for ice on refrigerant lines; if present, shut the system off to thaw.
If the unit still runs continuously after these steps, it’s time for professional air conditioner service.
About Nor‑Can Heating & Air; Edmonton’s Cooling Specialists
Based on the city’s north side, Nor‑Can Heating & Air has kept Greater Edmonton homes comfortable for more than a decade. Our factory‑trained technicians deliver quick diagnostics, 24/7 emergency repairs, and meticulous air conditioner service that restores efficiency and prolongs equipment life.
From coil cleaning to smart‑thermostat integration, we handle every detail so you can enjoy summer without sweating the utility bill.
Ready to stop your AC from running marathon cycles? Call to book service online today and reclaim cool comfort.
