The sudden silence from your furnace on a chilly Central Oregon evening can be a jarring sound, or rather, the lack of one. When the blower motor stalls, the pilot light goes out, or the system simply refuses to fire up, your home’s comfort hangs in the balance. Instead of panicking, it helps to understand the potential culprits behind the quiet. You’re likely asking yourself, “What can cause a furnace to stop working?”
Our experts at Bend Heating & Sheet Metal are here to demystify these common heating issues. We’ll walk you through the usual suspects behind a furnace failure, from simple fixes to more complex problems, helping you stay warm, safe, and prepared for the cold.
Common Reasons Your Furnace May Have Failed
Understanding the potential causes of a furnace failure can help you identify a problem early and, in some cases, safely resolve it yourself.
1. Dirty or Clogged Air Filter
This is, by far, the most common reason for a furnace to stop working. A clogged filter restricts airflow, causing your system to overheat. Most furnaces have a safety feature that automatically shuts off the unit to prevent damage. The warning signs are often weak airflow or the furnace cycling on and off.
What to do: Check your air filter monthly during peak heating season. If it’s visibly dirty, replace it. Clean filters help your furnace run efficiently and prevent unnecessary strain.
2. Thermostat Problems
Your thermostat acts as the command center for your heating system, telling the furnace when to turn on, how long to run, and when to shut off. If it’s malfunctioning, your furnace may receive incorrect signals—or none at all—resulting in no heat, short cycling, or running constantly.
What to do: Check that the thermostat is set to “Heat,” the temperature is set above the current room temperature, and the batteries are fresh. Still having issues? It may be time for a professional evaluation or an upgrade to a smart thermostat.
3. Ignition or Pilot Light Issues
Modern furnaces use an electronic ignition or a pilot light to ignite the gas. If your furnace has a pilot light, it could have been blown out. If it has an electronic ignition, a faulty ignitor can prevent the system from starting. You might hear clicking sounds without the furnace firing up.
What to do: Check your electrical panel for any tripped breakers. Reset if needed, but if the issue keeps happening, it could be a sign of a deeper electrical problem requiring professional attention.
4. Safety Shut-Off and Sensor Failures
Furnaces are equipped with multiple safety sensors. If a sensor detects an issue, like a clogged exhaust vent or a dirty flame sensor, it will shut the furnace down to prevent carbon monoxide leaks or other hazards.
What to do: This is a critical safety feature and a strong indicator that you should not attempt a repair on your own. If your system is cycling on and off, showing error codes, or not running at all, call the Bend Heating team for a professional inspection.
5. Blower Motor Problems
The blower motor is responsible for circulating warm air throughout your home. If the motor fails, the furnace may still be producing heat, but it won’t be distributed. You’ll likely notice the furnace running but feel little to no heat from your vents.
What to do: First, check your air filter, as restricted airflow can strain the blower motor. If the filter is clean and the airflow is still weak or inconsistent, it’s time to have the motor inspected. Blower motors can wear out over time, especially in older systems, and may require repair or replacement to restore full function.
When to Call the Professionals
While simple troubleshooting can be effective, some issues require the expertise of a professional. If you’ve tried the basics and your furnace is still not working, it’s time to call in the experts. Don’t attempt to repair ignition systems, gas lines, or electrical components yourself, as this can be dangerous.
At Bend Heating & Sheet Metal, our certified technicians are experts in diagnosing and repairing all types of furnace problems. We’re equipped with the tools and knowledge to get your heat back on safely and efficiently.
Stay Warm and Safe This Winter
Understanding what can cause a furnace to stop working gives you the power to respond quickly—and avoid bigger problems down the line. If your system is showing signs of trouble, don’t wait. Quick attention can prevent more costly repairs and keep your home comfortable through the coldest months.
Need help fast? Contact Bend Heating today for expert furnace diagnostics and repair. We’re here to keep Central Oregon warm and running all season.