Check these before you call
- The thermostat. Set to Cool, fan on Auto, and a few degrees below the room temperature.
- The furnace filter. A clogged filter starves the indoor coil of air, the coil ices over and cooling stops. If you see ice on the copper line outside or on the coil, turn the air conditioner off and run the fan on its own so the ice can melt before anyone works on it.
- The power. Central air has its own breaker in the panel and a disconnect box on the wall beside the outdoor unit. Check both.
- The outdoor unit. It needs to breathe. Clear away grass clippings, leaves and plants growing into the fins.
Built for a humid 30 °C
Ontario's Building Code designs cooling across Ottawa around a July day of 30 °C with a wet-bulb temperature of 23 °C. In plain terms, a hot day that's also very humid. On days like that an air conditioner runs for hours without stopping, and a weak part that got through June gives out. If yours sounded rough or struggled last summer, a spring check beats a breakdown in a heat wave.
Low on refrigerant means a leak
Refrigerant isn't used up. If a system is low, it's leaking somewhere, and topping it up without finding the leak means paying for the same refrigerant again next summer. The technician looks for the leak and tells you whether it's worth repairing. Older systems that use R-22 are the hard case: R-22 has been phased out in Canada, so it's scarce and costly, and replacement is often the better choice.
Water around the furnace in summer
An air conditioner pulls a lot of water out of the air, and it drains away through a small pipe or a condensate pump near the furnace. If that drain plugs or the pump fails, water spills onto the floor. Turn the air conditioner off and call. Some systems have a float switch that shuts cooling off on purpose when the drain backs up.