6 Reasons Your Furnace Isn’t Working

The furnace is a key part of the HVAC system, heating the home during the winter season. But when it starts blowing cool air instead of hot air, homeowners are charged with the task of figuring out why. Here are a few reasons a furnace may not be working properly.

  1. Malfunctioning thermostat

The first thing to check is the thermostat. If the fan is set to “on”, then the system will be blowing cool air. Switching the fan to “auto” will cause it to turn on only when the furnace is producing heat.

Also, check for a low thermostat battery. Some systems have self-contained batteries that will need to be replaced.

Improper wiring or wiring that isn’t compatible with the HVAC system can also cause problems with the furnace. This issue should be addressed by a professional technician. 

  1. Clogged filter

The HVAC filter is responsible for removing dust, dirt, pollen, and other contaminants from the air before it is sent throughout the home. But over time, the filter can become clogged and make it difficult for air to pass through. Inspect the filter and be sure to replace it once every three months.

A clogged filter can also cause the furnace to overheat, forcing the system to cool itself down by blowing cool air. After installing a new filter, restart the system and wait a few minutes for the air to become warm.

  1. High limit switch failure

The highlight switch can fail if the furnace overheats multiple times. This can cause the fan to turn on to cool the system. You’ll need to call Tucker Hill for professional HVAC service to address high limit switch failure.

  1. Clogged condensate line

A clogged condensate line can trip a switch in the furnace that prevents burners from igniting. This can cause cold air to blow through the system. Condensate lines can be cleaned by HVAC technicians.

  1. Deficient fuel source

If an oil furnace isn’t working, check the tank to make sure it isn’t empty. Similarly, a gas furnace may stop working if the gas valve is closed. An electric furnace should be turned on and plugged in. If it’s still not working, the cause could be a blown fuse or breaker.

  1. Leaking ducts

Leaky ducts can allow cold air to get in, causing the system to blow cool air even when the furnace is working properly. You’ll need a professional inspection to identify leaks in ductwork.