11 Simple Checks to Troubleshoot A Broken Furnace

When your furnace stops working, don’t call us.  Well, not right away.  That’s because there are a number of simple fixes you can try before scheduling a service call and possibly incurring an unnecessary charge.

1. Change your filter

Dirty filters are the #1 reason furnaces stop working.  Clogged filters can cause overheating and are responsible for the vast majority of furnace problems!  Luckily, this is an easy fix.  Simply change the filter. To keep your furnace running smoothly, install a new filter every month.

2. Press the reset button

This works for computers and furnaces!  Hitting the reset button may fix any problem that you are having with your gas furnace. If the unit still doesn’t start, wait 30 minutes and press the reset button again. Repeat at least once more.

3. Check the door cover

If the door cover is not on perfectly, your furnace will not start. This happens commonly after a filter change.

4. Open more registers

If more than 20% of the registers are closed this can cause high resistance and unnecessary heat build up in the furnace.  It’s okay to keep some registers closed in unused rooms in order to save on energy costs… but do not exceed 20%.  (If you have ten rooms, don’t close more than two registers.)

5. Check the power switch

Sometimes switches get turned off by mistake.  Check the switch to be sure it is in the “ON” position.

6. Look for blown fuses or tripped circuit breakers

Some furnaces have a separate power entrance, usually located at a different panel near the main entrance panel. Some furnaces have fuses mounted in or on the unit. If yours does not, check the main panel.

7. Check the thermostat.

The selector switch should be on “Heat.” If necessary, raise (or, for an air conditioner, lower) the setting 5 degrees. By setting the temperature higher than the actual room temperature, this will kick start your gas furnace to turn on and begin to warm your room.  Check the emergency switch to make sure that it’s “ON.”

8. Check the gas supply

Make sure the gas is turned on and the pilot light is lit.

9. Clear snow or ice, or other debris from the furnace venting

10. Put fresh batteries in the programmable thermostat

11. Make sure the blower fan is on

Not all furnaces have a blower on/off button, but if yours does, check it just in case someone accidentally bumped into it.

Chances are, one of these steps will resolve the problem. Still having problems? Contact Indoor Air Quality.