A tripping breaker or ice on the lines means switch the cooling off
If the breaker for the outdoor unit trips, reset it once at most. If it trips again, leave it off. A breaker that keeps tripping is protecting the wiring from a fault, often a failing compressor, a shorted fan motor or a worn capacitor. Resetting it over and over can turn a modest repair into a larger one.
Ice on the copper lines at the outdoor unit, or frost on the coil above the furnace, is another reason to stop. Set the thermostat to off and turn the fan to on. Moving air thaws the coil in a few hours and stops meltwater from overflowing the drain pan. Ice usually points to low airflow, from a blocked filter or closed vents, or to low refrigerant from a leak.
A burning smell, a loud grinding or a humming outdoor unit with a fan that will not spin are all reasons to turn the system off at the thermostat and leave it off until a technician has looked. None of these are dangerous to leave switched off. They are only hard on the equipment if it keeps running.
Warm air from the vents usually has a short list of causes
Start with the simple things. Check that the thermostat is set to cool and a few degrees below the room temperature. Check the furnace filter, since a clogged one starves the coil of air. Make sure the switch beside the outdoor unit is on and that nothing is piled against it. Grass clippings, cottonwood fluff and leaves on the outdoor coil can cut cooling noticeably.
If the indoor fan runs but the outdoor unit is silent, the cause is often a failed capacitor or contactor. These are common, quick to test and usually a straightforward repair. If the outdoor unit runs but the air is only a little cool, the refrigerant charge may be low, and that almost always means a leak somewhere in the system.
Rooms that cool unevenly, with the upper floor much warmer than the basement, are a different matter. That is more often about ductwork and airflow than a fault in the air conditioner, and a technician can tell you which it is.
Water near the furnace is usually a blocked drain
An air conditioner pulls moisture out of the air, and that water runs from the coil into a pan and down a drain line. When the line clogs with algae or debris, the pan overflows and water shows up on the floor beside the furnace. It looks worrying, but it is usually a cleaning job rather than a broken part.
In the newer houses around Fall Fair Way, Fletcher Road, Royal Winter Blvd and Binhaven Blvd, the air conditioner coil often shares its drain with a high-efficiency condensing furnace. A blockage in that shared line can cause trouble in both seasons, and some systems have a safety switch that shuts the cooling off when the pan fills. You can wipe up the water and turn the cooling off. Leave the drain line and the coil to a technician, who can clear it and check the switch.
Refrigerant work belongs to a compulsory trade in Ontario
Finding and fixing a refrigerant leak, recovering refrigerant and recharging a system is regulated work in Ontario. Work is performed by 313A refrigeration and air conditioning mechanics. Where a repair also involves the gas furnace that houses the coil and blower, work is performed by TSSA-certified gas technicians.
A system low on refrigerant has a leak. Topping it up without finding the leak only buys a short time. A proper repair locates the leak, fixes it where that is practical, and then charges the system to the manufacturer's figure. If the leak is in a coil that cannot reasonably be repaired, you will hear that plainly, along with what the alternatives would be.
A repair visit follows clear, simple steps
The technician starts by asking what you noticed and when. Then they check airflow, the electrical parts, the drain and the refrigerant pressures, and show you what they found. You get the repair price in writing and decide before any part is fitted.
Common parts such as capacitors, contactors and fan motors are often on hand. Some parts, especially for older or less common systems, have to be ordered. The aim is to get your central air cooling again within the season wherever parts allow, and if a part will take longer, you will know that up front.
Repair or replace depends on the age and the type of system
A system that is reasonably young with a single failed part is almost always worth repairing. An older system with a failed compressor, or a leaking coil on equipment that uses a refrigerant no longer made, is often better replaced. You get both prices so you can weigh them.
If replacement makes sense, see air conditioning installation, or look at heat pumps, which cool in summer and help heat in winter. A yearly maintenance visit in spring catches blocked drains and worn capacitors before the first hot week, and helps keep the manufacturer's warranty terms met.