Air Conditioner Leaking Water in Calgary? Switch It Off, Then Read This
Switch the cooling off at the thermostat straight away and keep the water away from anything electrical. In a Calgary basement the water under the furnace is almost always condensate that has stopped draining — a blocked line, a full pan or a failed pump — and occasionally a coil that froze and is now thawing. Neither is dangerous once the system is off; both need a technician before it runs again. Call (825) 395-7447 and our assistant puts you through live.
People are surprised that an air conditioner makes water at all in a city this dry. It does: the indoor coil above the furnace is colder than the dew point, moisture condenses on it the way it does on a cold glass, and on a 30 °C afternoon with the system running for hours that adds up to litres. All of it is supposed to collect in a pan and leave through a small plastic drain line to the floor drain or a condensate pump. When that path is blocked, the water goes where gravity sends it — the furnace cabinet, the floor, the finished rec room next door.
This page is the first ten minutes: switching off, containing the water, the two things you can safely look at yourself, and when it is a same-day call. Below that, the reasons the drain fails in a Calgary house, why a frozen coil looks like a leak, and what the repair typically involves.
What to do, in order
Cooling off at the thermostat
Set the thermostat from cool to off, and leave the fan on auto or on. This stops the coil making more water and, if it has frozen, lets it thaw. Do not just turn the temperature up — the compressor may keep cycling.
Contain what is already there
Towels, a tray, a bucket under the drip. Move boxes, rugs and anything stored beside the furnace. If the furnace sits on a finished floor, the water under the cabinet matters more than the puddle beside it — a wet furnace base rusts fast.
Cut the power if water is near it
If water is running down the furnace cabinet, pooling around the furnace's electrical box, or anywhere near the outdoor unit's disconnect, switch the furnace off at its wall switch and the air conditioner off at the breaker. Then leave it to the technician.
Look for ice
Check the copper lines at the furnace and, if you can see it, the coil housing above the furnace. Frost or a block of ice means the leak is a thaw: the coil froze from a blocked filter, a low charge or a failed blower, and it is now dripping. Leave the fan running to melt it; do not chip at it.
Check the drain line and the pan
Follow the thin PVC or vinyl line from the coil housing to where it ends. A line that ends in standing water, a pan that is full, or a condensate pump that is silent and full tells you which fault you have. If there is a cap on the line, opening it and pouring a cup of water through will show whether it is blocked.
Call
Our assistant asks what you found — ice, a full pan, a silent pump — and your postal code, then connects you live to a technician from our network. On a 32 °C day in July this is a same-day call for most of the city; say so if someone at home is elderly or unwell.
Call a professional immediately if…
- Water is reaching the furnace's electrical components, the control board or the outdoor disconnect.
- The furnace cabinet is wet inside — condensate soaking into a furnace corrodes the heat exchanger over a season.
- The coil is a block of ice rather than a light frost; a frozen coil that keeps running damages the compressor.
- The water has reached a finished floor, drywall or carpet in the next room — the cost is now in the flooring, not the repair.
- It is a heat wave and someone at home is elderly, unwell, pregnant or very young.
What happens once you call
The technician clears or replaces the drain line, cleans the pan, replaces a failed pump, or finds the reason the coil froze — a blocked filter, low refrigerant from a leak, a slow blower. A blocked drain is usually fixed on the first visit. A frozen coil from low refrigerant leads to a leak search, because topping up a leaking system is not legal in Alberta either — the province's Ozone-depleting Substances and Halocarbons Regulation prohibits recharging leaking equipment.
Ask them to check the pan for cracks and the float switch that is supposed to shut the system off before it overflows; many older installs have none, and adding one is cheap insurance for a finished basement.
Why the drain fails in a Calgary house
The condensate line is a small pipe that runs downhill to a floor drain, and it is usually forgotten for years. Dust, algae and the fine grit of a dry city build up in it over a few summers until it blocks; the pan fills, and the overflow finds the furnace. A pump, where the drain is above the floor, fails the same way — or its float sticks, or it simply dies after ten summers of standing water. In a house where the air conditioner runs perhaps three months a year, the line sits stagnant for nine, which is exactly how the block forms.
The other cause is ice. A blocked filter, a weak blower or low refrigerant drops the coil below freezing and it grows a shell of ice during the day; when the system cycles off, the ice melts faster than the pan can drain and the water goes over the edge. That leak stops when the coil thaws and returns the next hot afternoon, which is the tell.
Water outside: the outdoor unit after a storm
Water pooling around the outdoor unit after a Calgary summer storm is rain and hail melt, not a fault — but hail is the moment to look at the unit. Flattened fins on the coil restrict airflow and can push the indoor coil toward freezing, which becomes an indoor leak a week later. If the fins are matted or the fan housing is dented, photograph it before anyone works on it; the AC repair page covers what hail does and when it is an insurance conversation.
Questions
Is it safe to keep running the air conditioner if it is only dripping a little?
No. A small drip is a blocked drain or a freezing coil, and both get worse with every cycle — the pan overflows into the furnace, or the ice thickens until the compressor is straining. Switch cooling off, leave the fan on, and have it looked at. An afternoon without cooling costs less than a rusted furnace or a compressor.
Can I clear the condensate line myself?
Often. If the line has an open cap near the coil, pouring a cup of water through it shows whether it drains; a wet/dry vacuum on the outlet end will pull a soft blockage through. If the line is buried in a wall, runs to a pump, or you cannot see where it ends, leave it to the technician. Never use bleach in a line that ends at a pump.
Why is there ice on the pipes in July?
The coil is not getting enough air or enough refrigerant, so it drops below freezing. A filthy filter is the usual cause and the cheapest fix; a low charge from a leak is the expensive one. Turn cooling off and leave the fan running to thaw it, change the filter, and call — running it frozen damages the compressor.
Should I add a float switch?
Yes, if the furnace sits on or near a finished floor. A float switch in the pan shuts the system off before the water goes over the edge and costs a fraction of a flooring repair. Many older Calgary installs have none; ask the technician to add one while they are there.
Do you repair air conditioners yourselves?
No. hvaclines.ca is a live call-connection service run by PatchLead. We confirm the problem and where you are, then connect you on the same call to an independent technician from our network who does the work and quotes you directly. You pay nothing to use the service.