This might be a small device not technically connected to your furnace, but when it malfunctions, it can cause a range of problems, including:
- Furnace won’t start.
- Inaccurate temperature setting.
- Furnace won’t turn off.
- Heat keeps switching on and off.
Depending on what type of thermostat you have and its age, you may need to check if it is level, is past its reasonable lifespan or has dirt buildup. Many times, you won’t know the issue lies with your thermostat until you get it checked out.
A dirty filter is another small part of your system that can cause some large problems–and a lot of them. They include:
- Restricted airflow.
- High power bills.
- Dirty air ducts.
- Bad indoor air quality.
- Inefficient heating.
One definite way to tell if you need to change your air filter is by visually examining it in the light. Can you see through it? If not, it is time to change it, and you might notice your furnace problem disappears afterward.
3. Limit Switch
If your blower is running non-stop, the issue could lie with the limit switch. This switch is responsible for turning on the blower when the air in the furnace warms up enough. It is also responsible for turning off when your air reaches the desired temperature.
So if your furnace keeps blowing and blowing, you may have a problem with the limit switch.
2. Pilot Light or Ignition Control
Signs of an abnormal pilot light include:
- Yellow flame.
- Flickering flame.
- Short flame.
With ignition control, you might notice:
- Heat won’t come on.
- Flashing light for “ignition failure.”
- Blowing cold air.
Sometimes, as a safety feature for this problem, your unit will cut off. If it is just a pilot light or ignition control issue, your unit won’t be broken down for good.