A dead furnace is stressful, but most of what happens in the first hour determines whether it’s a quick fix or a much bigger problem. Here’s what to actually do, in order.
Step 1: Check the Basics First
Before calling anyone, check these three things — they solve a surprising number of “no heat” calls on their own:
- Thermostat — is it set to Heat, and is the temperature set above the current room temperature? Check batteries if it’s battery-powered.
- Breaker panel — has a breaker tripped for the furnace circuit?
- Furnace switch — many furnaces have a wall switch near the unit, styled like a light switch. Make sure it hasn’t been bumped off.
Step 2: Check the Filter
A severely clogged filter can cause a furnace to overheat and shut itself down as a safety measure. If your filter is visibly caked with dust, replace it and see if the furnace restarts after a few minutes.
Step 3: Look for an Error Code
Most modern furnaces have a small window showing a blinking light code. Take a photo of the blink pattern — it tells a technician exactly what safety fault the furnace is reporting before they even arrive, which speeds up the repair.
What to Skip
Don’t take apart the furnace cabinet, don’t reset the system repeatedly hoping it “catches,” and don’t attempt any gas line or ignition work yourself. Repeated reset attempts on a system with an actual fault can sometimes make the underlying problem worse, and gas components should only be handled by a TSSA-licensed technician.
When to Call
If the basics check out and the furnace still won’t run — or if you smell gas at any point — stop troubleshooting and call a technician immediately. In a Durham Region winter, a no-heat situation isn’t something to sit on overnight, especially with young kids, elderly family members, or pets in the house.
Our dispatcher is available 24/7, and a technician can typically be on-site within 60 minutes.