Furnace cool and running constantly? Here’s how to fix it.

February 3, 2022

Image Credit to One Beautiful Life Photo

Is your furnace fan running continuously while blowing cool air into your living space? It could be in lockout mode. 

If you have a high-efficiency gas furnace, this can periodically be an issue since these units drain water as they operate. When it’s cold out, that water can freeze, plugging the pipe that drains water to the outside. 

Check for an approximately on- inch plastic pipe that drains to the outside. This is your condensate line. If you see that snow has built up beneath it and/or the water flowing out of it has frozen, you can fix your system by doing these things:

How to fix lockout mode on your furnace

First: Dislodge the ice by pulling it from the pipe. Or try pouring hot water over the pipe until the ice plug melts.

Second: Once the ice plug is gone, go back inside and check your system. If the fan is still running, it’s probably still in safety lockout mode. Reset it by turning it off at the breaker for about 30 seconds; this reboots your furnace’s control board. (You may also need to reboot after a power outage.) Once you turn it back on, it should function normally.

Third: Keep your air filters clean or replace them regularly. If your filters are clogged, the furnace’s heat exchanger can start to overheat, kicking your furnace into lockdown mode. Keep it functioning by keeping your filters clear. 

What if your furnace still isn’t working?

If you’ve cleared the ice from the condensate line and reset your furnace at the breaker and it’s still not working, give your service technician a call. (You can text or call us at 360-491-7450.)

P.S. If you have a heat pump… 

If your heat pump isn’t heating your home properly, you can set your thermostat for emergency heat mode (EM HEAT or EHEAT on the display pad). This keeps the indoor portion of your home warm temporarily until a service technician is available to check it out.

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