A furnace breakdown is never convenient. They could happen in the middle of the night, or on a holiday! Before you call your HVAC repair company, run through these steps to see if it is a quick fix.
No heat and no air coming out of vent
If you are experiencing this with your heater then communication has been lost between the thermostat and the main unit, which is caused by a power failure.
- Change the batteries in your thermostat. Sometimes the screen will still work on the thermostat when the batteries are bad, but there isn’t enough power left to send a signal to the furnace
- Check the breaker in your main panel. This should be clearly labeled “heat”, “furnace”, or “AHU”. Even if the breaker looks set, go ahead and reset it to be sure
- Check for a light switch near your furnace. This switch controls the power to the furnace and all to often we find them OFF after someone has gone into the attic
No heat, but air coming out of vent
Furnaces have many safety functions, and the scenario of no heat with normal air coming out of the vent is one of them. If your furnace fails to light then the blower will come on run non-stop as a safety precaution.
- Look for a sight-glass and a flashing light on your furnace. If there is an error with the unit then you should see the lights flashing in a pattern. Make note of the pattern or record it with your phone and then reset the power. Sometimes it is just a one time issue, sometimes it continues. If it continues, call an HVAC professional.
Furnace cuts on and off intermittently
This issue can be tricky and can be caused by several different things, but some of the most common are: dirty air filter, corroded flame sensor, and other intermittent failures.
- Replace your air filter. If the air filter gets too dirty, then the furnace wont get enough air and will overheat. Once it cools down, the furnace will come back on.
- With the power off, you can remove the door to the burner compartment and look for the flame sensor. It is a thin metal rod positioned in front of the burners. They commonly get corroded and need to be sanded down. It is recommended that you have an HVAC professional complete this task for you.
- Other common failures are: circuit board, pressure switch, weakening safety switches, induced draft motor, ignitor plate, blower motor.
Please keep in mind that working on a furnace is a very dangerous task and should only be handled by qualified professionals. If you have checked off these basic items and your furnace is still not heating, then call your local HVAC repair company to come out and take a look.