AC Running But
Not Cooling?
Your AC is running — the outdoor unit is on, the fan is blowing — but your London Ontario home is not getting cold. Here are the 6 most likely causes, ranked from most to least common, with the DIY checks to try first before calling a technician.
Check These Two Things First Before Calling
1. Your air filter: Pull it out and hold it to the light. If you cannot see light through it, replace it now. A clogged filter is the #1 cause of AC not cooling in London Ontario. 2. The outdoor unit: Make sure nothing is blocking the condenser — grass clippings, debris, cottonwood. Gently rinse with a garden hose if clogged. If cooling doesn’t improve after these two checks, read on or call (647) 550-4220.
Why Your AC Is Running But Not Cooling in London Ontario
Ranked from most to least common based on Hawana’s London Ontario service calls.
Dirty or Clogged Air Filter
A clogged filter restricts airflow through the evaporator coil. Without adequate airflow, the coil cannot absorb heat from your home’s air — so the AC runs constantly but cooling is dramatically reduced. Severe restriction causes the coil to freeze over, blocking airflow entirely. London Ontario cottonwood season in May–June dramatically accelerates filter clogging in homes near parks and trees.
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 do not use up refrigerant. If the charge is low, there is a leak somewhere. A low charge causes the AC to run constantly without reaching target temperature, and eventually causes the evaporator coil to freeze. Topping up the refrigerant without fixing the leak is a temporary fix that accelerates compressor damage.
Dirty Condenser Coil (Outdoor Unit)
The outdoor condenser coil releases heat from your home into the outside air. If it is coated in dirt, grass clippings, or cottonwood fluff (very common in London Ontario from May through July), it cannot reject heat efficiently. The AC runs but cooling capacity drops significantly. You may notice the outdoor unit feels extremely hot and the air blowing out the top is not as warm as it should be.
Failing or Failed Compressor
The compressor is the heart of the AC. When it weakens, it cannot build adequate refrigerant pressure — the system runs but cooling is minimal or absent. A failing compressor often shows up as the AC running almost constantly, the outdoor unit running while the indoor unit blows warm air, or unusual sounds from the outdoor unit. Compressor failure is the most expensive AC repair, and on units over 10–12 years old, replacement of the full system is often more economical.
Frozen Evaporator Coil
When the evaporator coil (inside) freezes over, it becomes a solid block of ice that airflow cannot pass through. The AC runs but blows warm or barely-cool air. Causes include a clogged filter (cause #1), a refrigerant undercharge (cause #2), or a blocked or closed supply vent. Signs: ice visible on the refrigerant lines coming from your furnace or air handler, or water dripping near the indoor unit as the ice melts.
Oversized AC — Short-Cycling
An oversized AC cools the home too quickly and shuts off before completing a full cycle, without removing adequate humidity. The home feels cool but clammy and uncomfortable, and temperatures vary widely between rooms. This is a design issue from an improper installation, not a repair issue. More common in newer London Ontario subdivisions where a contractor installed the largest unit that would fit without a proper heat-load calculation.
⚠️ Call Hawana Immediately if Any of These Apply
Call (647) 550-4220 right away if: the outdoor unit is making loud banging or grinding noises, you see ice on the refrigerant lines and a new filter did not fix it within 4 hours, the home will not cool below 28°C on a moderate day despite the AC running constantly, water is pooling near the indoor air handler, or the outdoor unit is running but the indoor fan has stopped. Do not continue running the system in these conditions.
AC Not Cooling Reviews — London Ontario
5.0 stars · 139 Google reviews · Read all reviews ↗
“Called Hawana because our AC was running constantly but the house would not go below 27°C. Abdullah found a slow refrigerant leak that had been depleting the charge over months. Repaired and recharged same day. Down to 22°C in two hours. Explained exactly what happened and how to spot it next time.”
“Our AC was running but not cooling at all. Followed the checklist — changed the filter, checked the outdoor unit. Nothing improved. Called Hawana. Found a failing capacitor — the fan motor was barely running, so the condenser wasn’t rejecting heat properly. Replaced same visit. House cool again in under an hour.”
AC Not Cooling FAQs — London Ontario
Why is my AC running but not cooling my London Ontario home?
My AC is blowing cold air at the vent but the house will not cool down. Why?
My outdoor AC unit is running but no cold air is coming from the vents. What is wrong?
How much does it cost to fix an AC that is not cooling in London Ontario?
Can I do anything to help my AC cool better during a London Ontario heat wave?
AC Still Not Cooling? Call Hawana — Same Day.
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