AC Running But
Not Cooling?
Your AC is running — the outdoor unit is on, the fan is blowing — but your London Ontario home isn't getting cold. This is one of the most common summer HVAC calls. Here are the 6 most likely causes, ranked from most to least common, with the DIY checks to try first before calling a technician.
6 Reasons Your AC Is Running But Not Cooling in London Ontario
Ranked from most to least common. Try the DIY fixes first — they might save you a service call.
Dirty or Clogged Air Filter
A clogged filter restricts airflow through the evaporator coil. Without adequate airflow, the coil can't absorb heat from your home's air — so the AC runs but cooling is dramatically reduced. Severe filter restriction causes the coil to freeze over, blocking airflow entirely.
Low Refrigerant — Leak in the System
Refrigerant is the fluid that transfers heat from inside your home to the outdoor unit. AC systems are sealed — they don't "use up" refrigerant. If the charge is low, it means there's a leak somewhere in the system. A low charge causes the AC to run continuously without achieving target temperature, and eventually causes the evaporator coil to freeze.
Dirty Condenser Coil (Outdoor Unit)
The outdoor condenser coil releases heat from your home into the outside air. If it's coated in dirt, grass clippings, or cottonwood fluff (very common in London Ontario in spring), it can't reject heat efficiently — the AC runs but cooling capacity drops significantly. London Ontario's cottonwood season in May–June is a major contributor to this problem.
Failing Compressor
The compressor is the heart of the AC system. When it weakens, it can't build adequate refrigerant pressure — the system runs but cooling is minimal. A failing compressor often comes with unusual sounds from the outdoor unit, the AC running almost constantly, or the outdoor unit running while the indoor unit blows warm air. Compressor failure is the most expensive AC repair.
Frozen Evaporator Coil
When the evaporator coil (indoor) freezes over, it becomes a block of ice that airflow can't pass through. The AC runs but blows warm or barely-cool air. Causes: clogged filter (see #1), low refrigerant (see #2), or a blocked/closed vent in the home. Signs: ice visible on the refrigerant lines coming from your furnace/air handler, or water dripping near the indoor unit.
AC Oversized for the Home
An oversized AC short-cycles — it cools the home quickly but doesn't run long enough to dehumidify the air. The home feels cool but clammy, and temperature is uneven. This is a design problem from an improper installation, not a repair issue. More common in newer subdivisions where a contractor installed the largest unit that would fit without doing a proper heat-load calculation.
⚠️ When To Call Hawana Immediately (Don't Wait)
Call (647) 550-4220 immediately if: the outdoor unit is making loud banging or grinding noises, you see ice on the lines and replacing the filter didn't fix it within 4 hours, the home won't cool below 28°C+ on a hot day despite the AC running constantly, or there is water pooling near the indoor air handler. Same-day emergency service available — no overtime charges.
AC Not Cooling — Repair Cost London Ontario 2026
Written quote after diagnosis — before any work begins. No overtime charges.
AC Diagnostic
- Full system inspection
- Temperature drop measurement
- Electrical component testing
- Refrigerant pressure check
- Written quote before any repair
- Same-day service available
Capacitor / Contactor
- Run or start capacitor replacement
- Contactor replacement
- Parts always on the truck
- Typically fixed within 1 hour
- No emergency surcharge
Refrigerant Leak
- Leak detection and repair
- System recharge to spec
- Most leaks fixed same visit
- No "top-up without repair" — we fix the root cause
* All prices in CAD. Same-day diagnostic and repair available. Written quote after diagnosis before any repair begins. No overtime charges.
AC Not Cooling Reviews — London Ontario
Real diagnostics, real fixes, real same-day results.
"Called Hawana because our AC was running constantly but the house wouldn't go below 27 degrees. Abdullah found a slow refrigerant leak that had been quietly depleting the charge over months. Repaired the leak and recharged same day. The difference was immediate — down to 22 in two hours. He explained exactly what happened and how to spot it early next time. Great technician."
"Our AC was running but not cooling our Old South home. I followed the DIY checklist on this page — changed the filter, checked the outdoor unit. Nothing helped. Called Hawana. Abdullah arrived within 3 hours, found a failing capacitor that was affecting compressor performance, replaced it same visit. House was cool again in under an hour. The diagnostic was $89 and the repair was exactly what they quoted. No surprises."
AC Not Cooling — FAQs for London Ontario Homeowners
Why is my AC running but not cooling my London Ontario home?
My AC is blowing cold air at the vent but the house won't cool down. Why?
My outdoor AC unit is running but no cold air is coming from the vents inside. What's wrong?
How much does it cost to fix an AC that's not cooling in London Ontario?
Can I do anything to help my AC cool better during a London Ontario heat wave?
AC Not Cooling in London Ontario? Call Hawana.
Same-day diagnosis. Written quote before any repair. TSSA certified. No overtime charges. 139 five-star reviews.
Written quote · 30-day guarantee · TSSA certified · No overtime
