Furnace Not Working? Check These 7 Things First

If your furnace is not working, check seven things before calling: the thermostat setting and batteries, the air filter, the furnace power switch, the circuit breaker, the furnace door panel, the gas valve, and the plastic vent pipes outside. A clogged filter and snow-blocked vents are two of the most common causes of a winter shutdown in Utah.

The checklist

• Thermostat: set to heat, set above room temperature, and with fresh batteries
• Filter: replace it if it is dirty. A clogged filter makes the furnace overheat and shut itself off
• Power switch: the light-switch-style switch on or near the furnace should be on
• Breaker: check the furnace breaker in the electrical panel
• Door panel: the furnace will not run if the front panel is not fully seated
• Gas valve: the handle on the gas line to the furnace should be parallel to the pipe
• Vent pipes: on a high-efficiency furnace, clear snow, ice and debris from the plastic intake and exhaust pipes outside

Read the blink code

Most furnaces have a small light on the control board that blinks a code when something is wrong. The key to the code is usually on a sticker inside the furnace door. Write down the pattern. It helps the technician arrive with the right part.

When to stop and call

Call right away if you smell gas, if a carbon monoxide alarm sounds, if the furnace starts and shuts off repeatedly, or if you see water pooling around it. If you smell gas or a carbon monoxide alarm is going off, leave the house first and call 911 or your gas utility from outside.

While you wait

Close off unused rooms, keep cabinet doors under sinks open so pipes stay warm, and use space heaters carefully, away from anything that can burn and never unattended.