Is Your Furnace Blowing Cool Air? What Could Be Wrong?When your furnace blows cold air, it could be something simple that you can fix easily, shortening the time your home grows uncomfortable. These tips may help you get it running again:

  • Check the thermostat to see if it’s set to “heat” and the fan is in the “auto” position. If it’s set on the “on” or “fan only” position, your heating system could be blowing cool air because the fan is running continuously, even after the equipment stops heating your home. Not all thermostats will run the fan independent of the HVAC system.
  • Turn the thermostat up and wait a few minutes. If you don’t hear a click, the thermostat may not be working.
  • Change the air filter if it’s dirty. Some systems will shut down if the airflow is insufficient to protect your safety and the equipment.
  • Inspect the ductwork and registers if just one room has cool air. It could be a ductwork leak or blocked registers.
  • Look at the circuit breaker to see if it has tripped. If so, turn the breaker to off and then back to on. If the circuit breaker is on, check the switch inside the system’s compartment and reset, if necessary.
  • Make sure that the gas valve to your home is open; the valve should be parallel to the gas line near where it enters your furnace.
  • See if the pilot is burning (if you have an older furnace with a pilot light). There could be a problem with dirt inside the pilot or the thermocouple. The thermocouple has to stay hot to keep the gas flowing. If the pilot goes out for any reason, the thermocouple will cool and turn off the gas supply. It may take a minute or two to warm the thermocouple enough when relighting the pilot. If the pilot continues to go out, use a can of compressed air to clean it out. If your equipment uses an electronic ignition system, you could have an issue with the flame sensor or hot surface igniter. Both of these parts can fail and may need to be replaced.

Should your furnace still not respond, contact the pros at Mowery Heating, Cooling and Plumbing, serving Indianapolis area homeowners for more than 40 years.

Our goal is to help educate our customers in Brownsburg, Indiana and surrounding areas about energy and home comfort issues (specific to HVAC systems). 

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