It happens every summer without fail. The temperature hits 32°C, you turn on your air conditioner — and nothing happens. Or worse, it runs but blows warm air. Or it trips the breaker the moment it kicks on.
You're not alone. AC failures spike dramatically during heat waves because systems that have been sitting idle run harder than ever, revealing problems that were lurking all along.
Here's what's most likely wrong — and what to do about it.
Most Common Reasons AC Fails in Hot Weather
1. Dirty or Clogged Air Filter
This is the number one cause of AC problems and the easiest to fix. A clogged filter restricts airflow so severely that the system overheats and shuts down. Check your filter first — if it's grey and thick with dust, replace it immediately. Filters should be changed every 1-3 months.
2. Low Refrigerant (Freon Leak)
If your system blows air but it's not cold, you're likely low on refrigerant. This happens when there's a slow leak in the system. Refrigerant doesn't "run out" — if it's low, there's a leak that needs to be found and repaired by a licensed technician before recharging.
3. Frozen Evaporator Coil
Ironically, your AC can freeze up in summer. If airflow is restricted (see: dirty filter) the evaporator coil gets too cold and ice forms around it. Turn the system off, let it thaw for 2-3 hours, replace the filter, then try again. If it keeps freezing, call a technician.
4. Tripped Circuit Breaker
During a heat wave, your AC runs longer and harder than normal. This can trip a circuit breaker — especially in older homes. Check your electrical panel. If the breaker keeps tripping, don't keep resetting it. A repeatedly tripping breaker signals a deeper electrical or mechanical problem.
5. Condenser Unit Blocked or Dirty
The outdoor unit (condenser) needs airflow to release heat. If it's surrounded by overgrown plants, fencing, or built up with debris from winter, it can't do its job. Clear at least two feet of space around the unit and gently rinse the fins with a garden hose.
6. The System Is Simply Too Old
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What To Do Right Now
- Check and replace the air filter
- Check the circuit breaker
- Clear space around your outdoor unit
- Turn the system to fan-only for 2 hours to let it reset
- If none of that works — call a technician
When to Call Grove Mechanical
If your system still isn't working after the steps above, you need a licensed technician to diagnose the problem. Grove Mechanical can assess the issue and discuss the appropriate service path and current scheduling availability. A qualified technician can determine whether repair or replacement makes more sense for the specific system.
Frequently Asked Questions
Why does my AC stop working during a heat wave?
Heat waves push AC systems beyond their design capacity. Common causes include a dirty air filter restricting airflow, a frozen evaporator coil from running the system too hard, a tripped circuit breaker from electrical overload, or low refrigerant. Start with the filter and breaker panel before calling a technician.
How long does it take to fix an AC that stopped working?
Simple fixes like filter replacement or resetting a breaker take minutes. Refrigerant recharges or component replacements typically require a same-day or next-day service call. During heat waves, Grove Mechanical prioritizes emergency cooling calls — call 604-371-4949.
Should I repair or replace my AC if it breaks down?
If your system is under 10 years old and the repair is under $500, repair is usually the right call. If the system is over 12 to 15 years old, or the repair cost exceeds 50% of replacement cost, a new system is the better long-term investment, after reviewing the current system and active provider terms.
Can I run my heat pump in cooling mode during a heat wave?
Yes — modern heat pumps are designed to cool as well as heat. Set your thermostat to cool mode and your desired temperature. If the system is not keeping up, check the filter and ensure the outdoor unit has at least 2 feet of clearance on all sides.