Quick checks (in order)
- Thermostat set to Cool, fan on Auto, setpoint 3°C below room temp.
- Air filter — a clogged filter is the #1 cause of weak cooling.
- Outdoor unit — clear leaves, grass clippings, and dryer lint from the fins. Hose it down gently.
- Outdoor breaker — there's usually a disconnect box beside the condenser. Flip off, wait 60 seconds, flip on.
- Indoor coil frozen? — If you see ice on the copper line, shut the system off and let it thaw for 4 hours. Then check the filter.
- Vents — confirm supply vents are open and return vents aren't blocked by furniture.
Symptoms that mean call a pro now
- Hissing or bubbling near the outdoor unit (refrigerant leak)
- Ice that keeps coming back after thawing
- Tripped breaker that won't reset
- Burning smell from the indoor unit