AC Running but Not Cooling During Ontario's Heat Wave? 7 Things to Check First

If your air conditioner is running all day but your home still feels warm, you are not alone. During an Ontario heat wave, many homeowners notice that their AC runs longer, cools more slowly, or struggles during the hottest part of the afternoon.

Some of that can be normal in extreme heat. But if your AC is blowing warm air, airflow feels weak, or the temperature keeps rising inside your home, there may be a real problem.

Quick Answer: Is It Normal for an AC to Struggle in a Heat Wave?

It can be normal for your AC to run longer during a heat wave, especially between 2 p.m. and 7 p.m. when outdoor heat, humidity, and sun exposure are at their highest.

But it is not normal if: The air from your vents feels warm, The AC runs for hours with no temperature drop, Your home gets hotter while the AC is on, Airflow is weak from multiple vents, Ice appears on the indoor or outdoor AC lines, The system makes buzzing, grinding, or rattling sounds, The breaker trips when the AC starts.

1. Do the Simple Vent Temperature Test

Let your AC run for at least 10 to 15 minutes. Then check the temperature of the air going into the return vent and compare it with the air coming out of a supply vent.

2. Check the Air Filter Before Anything Else

A dirty air filter is one of the most common reasons an AC struggles during extreme heat.

3. Look for Ice on the AC Lines

Ice on your AC is never something to ignore, even during a heat wave.

Contact Comfort Next for AC repair service in Aurora and nearby Ontario communities if your AC is not cooling properly.