The capacitor is a small cylindrical part inside your outdoor AC unit that stores and releases the burst of energy the compressor and fan motor need to start and keep running. It is cheap, but it fails often, especially after a run of hot Ontario days, and when it does the whole system stops cooling. A failed capacitor is one of the most common summer service calls we get, and usually a quick fix once a technician is on site.
Signs of a Bad AC Capacitor
- The outdoor unit hums but the fan does not spin (the classic symptom).
- The AC runs but the house is not cooling.
- A clicking sound from the outdoor unit as it tries and fails to start.
- The system starts and stops more often than normal (hard starting).
- A burning smell or a visibly bulged or leaking capacitor top.
What Causes a Capacitor to Fail
Heat
Extended high temperatures are the biggest killer. A capacitor sitting in a sun-baked outdoor unit through a GTA heat wave degrades faster.
Age
Most capacitors last 5 to 15 years. Failure becomes more likely as the unit ages, which is why capacitor issues cluster on older systems.
Power surges
Lightning and grid surges can weaken or destroy a capacitor instantly.
Wrong-rated part
A previously installed capacitor with the wrong microfarad rating runs the motor hot and shortens its life.
AC Capacitor Replacement Cost in Ontario
An AC capacitor replacement typically runs $185 to $300 installed in the GTA, including the diagnostic, the part, and labour. It is one of the least expensive AC repairs and is almost always a same-day fix. If a technician recommends replacing the capacitor along with a hard-start kit or contactor, expect the higher end of that range.
When to Call a Technician
Call EcoFrost as soon as you notice the humming-but-no-spin symptom or the system stops cooling. Running the AC with a failing capacitor strains the compressor, which is the single most expensive part to replace. A fast capacitor swap protects the compressor and restores cooling the same day, with no overtime charge on evenings or weekends.
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Book Same-Day AC Repair?Frequently Asked Questions
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