Why Is My AC Not Working?
London Ontario 2026

The run capacitor provides the voltage jolt needed to start and keep the compressor and fan motor running. It degrades over time — London Ontario’s hot summers accelerate this degradation. A failing capacitor starts losing capacity before it fails completely, meaning your system may work some days but struggle on hot days. A fully failed capacitor means the outdoor unit will hum but the fan won’t spin and the compressor won’t start.

Why it happens in London Ontario specifically: Summer heat above 30°C stresses capacitors harder than mild climates. Units in direct afternoon sun are most vulnerable. A capacitor that tests at the low end of spec in April may fail completely in August when ambient temperatures around the unit hit 40°C+.

Your AC’s 240V circuit has a dedicated double-pole breaker in your electrical panel, typically rated 30–50 amps. When the AC draws more current than the breaker rating — due to a starting fault, a failing compressor, or a genuine overload — the breaker trips. There is also an outdoor disconnect box near the outdoor unit. If a fuse blew or the switch was left off, the outdoor unit won’t start while the indoor blower runs normally.

When your air filter becomes severely clogged, airflow across the evaporator coil drops dramatically. The coil becomes too cold without sufficient warm air moving over it, and the moisture in the air freezes on the coil surface. A frozen coil cannot transfer heat — cooling stops entirely. London Ontario cottonwood season (May–June) can clog a 1-inch filter in 2–3 weeks during peak seed release.

Refrigerant is the substance that absorbs heat from inside your home and releases it outside. It circulates in a closed loop and does not get used up — it only leaves the system if there is a leak. A slow refrigerant leak causes the system to gradually lose cooling capacity over weeks or months.

Important: Adding refrigerant without finding and repairing the leak is a bandaid that lasts one season. The leak continues, refrigerant levels drop again next year. A proper repair finds the leak, repairs it, and recharges to manufacturer specification.

The contactor is an electrical relay switch that connects the high-voltage power supply to the compressor and fan motor when the thermostat calls for cooling. Over time, the contact points develop pits and burning from repeated arcing — eventually the contacts no longer make a solid connection and the outdoor unit won’t start. A failing contactor may cause the outdoor unit to start intermittently before failing completely.

As your AC cools the air, it removes moisture that drips off the evaporator coil into a drain pan and flows out through a condensate drain line. London Ontario’s moderately hard water deposits calcium and algae in this line over time. When it blocks completely, the drain pan fills and triggers a safety float switch that shuts the AC off entirely.

The outdoor condenser unit rejects heat by blowing air through the condenser coil. When the coil fins are packed with cottonwood seeds, grass clippings, or general debris, airflow is severely restricted. The system cannot reject heat efficiently — it runs longer, works harder, uses more electricity, and may overheat and lock out. London Ontario cottonwood trees release seeds in May through early July that can pack the condenser fins within 2–3 weeks.

The compressor is the heart of your AC system. Compressor failure is the most expensive AC repair and usually happens in systems that are 10–15+ years old, have had chronic refrigerant issues, or have been running with improper refrigerant charge over many seasons.

Repair vs replace decision: A compressor replacement costs $800–$2,000. On a system over 12 years old, this repair cost is often better invested in a new system that is more efficient, under full warranty, and won’t need another major repair in 2–3 years. Hawana provides honest guidance at every diagnosis.