Furnace won’t turn on? Start here.

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1. Check the thermostat

Make sure it’s set to HEAT and the temperature is a few degrees above the room. Try fresh batteries — a dead thermostat is one of the most common “no heat” calls. If yours is older, a loose wire behind it can be the culprit.

2. Check the power

Furnaces need electricity even to burn gas. Check that the furnace switch (it looks like a light switch near the unit) is on, and look for a tripped breaker in your panel. Flip a tripped breaker fully off, then back on.

3. Check the filter

A badly clogged filter can choke airflow enough to trip the furnace’s safety limit and shut it down. If yours is gray and caked, replace it — then give the furnace a few minutes to reset.

4. Check the gas

Make sure the gas valve to the furnace is open (handle parallel to the pipe) and that other gas appliances work. If you smell gas, leave and call your utility first — don’t troubleshoot.

5. Check the furnace door

Most furnaces won’t run unless the blower door is fully closed — there’s a safety switch behind it. If the panel was pulled for a filter change and not seated right, the furnace won’t fire.

6. Check the condensate drain

High-efficiency furnaces make water, and a clogged condensate drain or full float switch will shut the furnace off to prevent a leak. If you see water around the base, this is a likely cause.

7. Look for a blinking light

Through the little window on the furnace, a blinking LED is the furnace telling you its error code. Count the blinks — the legend is usually printed on the inside of the door. It’s a big head start on the diagnosis.

When to call a pro

If you’ve checked these and still have no heat — or the furnace lights and then shuts off, short-cycles, or smells off — it’s time to bring someone in. We offer same-day and after-hours furnace repair across the Salt Lake Valley, and we’ll quote the fix before we start. Staying ahead of breakdowns is exactly what an annual furnace tune-up is for.