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Furnace Not Working? The Furnace on and off Switch May Be the Problem

If your furnace is not turning on, it may be because the furnace switch is off instead of on. Your furnace has a furnace switch that controls power to the unit. If it's flipped off, your furnace won’t kick on, and you'll need to flip it back on to fix it.

How Does the Furnace Switch On and Off?

Believe it or not, furnace switches often get flipped on and off by accident. Anyone from a technician working on your furnace, to a child playing near the switch, could accidentally flip it without realizing or knowing what it is.

How to check for a flipped furnace switch

  • Check your furnace to see if it is trying to start up at all. If it is, the problem is likely not the switch. Your best bet is to check to see if your furnace is displaying a diagnostic light.

  • Many furnaces have a diagnostic light visible through a small clear viewing window on the lower front door of the unit. If you see a light flashing a pattern of blinks, the furnace may be experiencing a heating issue that created a lockout.

  • If your furnace is indeed experiencing a lockout, you'll need to reset it to activate normal operation.

    Record the number of flashes, then turn the power switch off and back on to reset the lockout. If normal operation is restored, you've successfully reset the lockout. If the diagnostic light persists, the issue must be investigated in order to restart the furnace.

  • Locate the furnace switch. It looks like a light switch, and is sometimes labelled as an “emergency switch.” It's usually located near or on your furnace unit. If you have an older system, it could be at the top of the basement staircase. If your furnace is in the attic, check the breaker.

    Make sure the switch was not accidentally turned off (it happens more than you'd think).

  • Is your furnace switch set to off? If it is, you've found the problem. Luckily, it's an easy fix. Switch it back on.

If these steps didn't help you get down to the bottom of your issue, consider other reasons why your heating unit won't turn on, the thermostat screen is blank, or there's no heat coming from the vents.

What To Do If Your Furnace Switch Has Been Flipped On to Off?

The good news about a flipped furnace switch is that the fix is really easy: just flip it back on!

Didn't work? If your furnace still is not working or your furnace won’t kick on, there is likely something bigger going on that will require a professional's perspective.

NOTE: This content is for informational purposes only, and HomeX and its affiliates disclaim all liability related to it. If you decide to perform any tasks based on this information, you assume all risks, including the risk of loss or damage to property or personal injury.

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