DIY Furnace Repairs

Your furnace has one job. When it fails to keep you warm, your kneejerk response is to call a pro. But how would you feel if the problem turned out to be a thermostat on the wrong setting or a clogged filter?

Furnaces are complicated, but some fixes are simple. You may be able to spare yourself a service fee with these troubleshooting tips:

If the Furnace is Short Cycling

Your furnace kicks on briefly and shuts down. The cycle repeats -- on and off, on and off -- without ever getting your warm. That’s called short cycling, and the filter or flame sensor could be at fault.

Check the filter: A dirty filter restricts airflow, causing the system to overheat and shut down. Remove the filter and hold it up to a light. If you can’t see the light through the fabric, replace it with a clean filter. As a rule, you should replace the filter every 30 to 90 days.

Clean the flame sensor: The flame sensor is a short metallic rod in the burner assembly. It’s a failsafe that prevents the furnace from leaking gas into the home. If it doesn’t sense a flame, it shut off the furnace. Soot and build-up can interfere with it, hence a malfunctioning furnace.

  • Open the furnace cabinet
  • Find the flame sensor. It’s the metal rod held in by a screw
  • Remove the sensor
  • Gently clean with steel wool
  • Place back into the bracket

Is your furnace still short cycling? You’ll need to bring a pro because this is a problem that will require expertise to solve.

If the Furnance isn’t Heating

Check the thermostat: Is it is set to “heat?” If your furnace fan is continuously running, check the fan setting. It should be set to ‘auto.’ If it’s on ‘on,’ the fan will run whether the furnace is on a heating cycle or not.

Check the pilot light: Take a peek inside the burner assembly. Do you see a standing blue flame? If not, you’ll need to ignite the burner. Consult the owner’s manual, and be careful! Maybe save this job to a pro. If the flame is any color other than blue -- yellow or green, perhaps -- that means there’s too much gas. Contact a pro!

Check the return vents: Is anything obstructing them? Are they closed?

Bottom line: If you’re not afraid to roll up your sleeves and get your hands a little dirty, you might be able to fix your furnace yourself. If not, turn to the pros at Mid-Florida Heating & Air by calling (352) 310-0022.