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Heating
Furnace Not Turning On? What to Check First
A simple checklist to run before you call when your furnace won't start — and the signs it needs a professional.
Start at the thermostat
Make sure it's set to HEAT and the set temperature is a few degrees above the room temperature. If the screen is blank, replace the batteries.
Check the power switch and breaker
Most furnaces have a switch that looks like a light switch on or near the unit. It's easy to bump it off by accident. Also check the breaker panel for a tripped furnace breaker.
Make sure the door panel is on tight
Furnaces have a safety switch behind the front panel. If the panel isn't seated properly, the furnace won't run at all.
Check the filter and vents
A dirty filter can cause the furnace to trip a safety limit and stop. Replace it and make sure supply vents and return grilles aren't blocked by furniture.