Check the Furnace FilterFirst and foremost, check the filter. Over time, the furnace filter will accumulate dirt and debris. That clogs the filter and impedes air flow. Even worse, accumulated dirt will lead to reduced indoor air quality, and may even prevent the furnace from turning on. A dirty filter is also a fire hazard.
Follow these steps to check your furnace filter:
- Turn off the thermostat and switch the furnace off.
- Check the filter every 30 days (set a reminder on your phone).
- Hold the filter to a light – if light cannot pass through, filter should be replaced.
- Remember: The arrows on the new filter point in the direction the air should flow.
- Make sure the access panel is secure.
Check the ThermostatOnce you have verified the furnace filter is clean and properly installed, check on the thermostat. The thermostat is the next likely cause for furnace troubles.
- First, be sure the thermostat is set to “heat,” and set the temperature 5 degrees higher than the current room temperature.
- A thermostat runs on batteries, so replace them often.
- Be sure the thermostat is not receiving false readings from sunlight, ovens, space heaters, or nearby lamps. If it is, the unit will send the wrong output to the furnace.