My furnace clicks but doesn't light — what's wrong?

This usually means the ignitor is failing or the flame sensor is dirty. The ignitor may glow but not get hot enough, or the flame sensor may not detect the flame, causing the control board to shut off gas flow as a safety measure.

Can a dirty filter really stop my furnace from working?

Yes. A severely clogged filter restricts airflow so much that the heat exchanger overheats, tripping the high-limit safety switch. The furnace shuts down to prevent damage. Replace the filter and reset the system.

How do I read the error codes on my furnace?

Open the lower furnace panel and look for a small LED light on the control board. It will flash a pattern — for example, 3 flashes then a pause. Consult your owner's manual or tell our technician the flash pattern when you call.

Furnace Not Working — Troubleshooting Steps

Furnace won't start? Follow these safe troubleshooting steps before calling for professional heating repair.

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Professional Furnace Not Working — Troubleshooting Steps in Asheville & Western NC

Safety First: What to Check Immediately

Before troubleshooting a furnace that isn't working, check for any unusual smells. If you smell gas (rotten egg odor), leave the house immediately, don't flip any switches, and call your gas company from outside. If there's no gas smell, you can safely proceed with basic troubleshooting. Check your thermostat — make sure it's set to "heat" and the set temperature is above the current room temperature. Verify that the thermostat display is active and batteries are fresh.

The Three Most Common Furnace Fixes

First, check your air filter. A completely clogged filter restricts airflow to the point that the furnace overheats and shuts down on its high-limit safety switch. Second, find your furnace's power switch — it looks like a regular light switch, usually on or near the furnace — and make sure it's on. It's easily bumped off accidentally. Third, check the breaker panel for a tripped HVAC breaker. These three checks resolve a surprising number of "furnace not working" calls in Western North Carolina.

Understanding Furnace Lockout

Modern furnaces have built-in safety controls that lock the system out when something goes wrong. If your furnace tries to start — you hear clicking or see the ignitor glow — but then shuts down after a few seconds, it's probably in lockout mode. This happens when the flame sensor is dirty, the ignitor is failing, the gas valve isn't opening, or the pressure switch detects a venting problem. Many furnaces display error codes through LED flashes on the control board. Count the flashes and share that information with your technician — it speeds up diagnosis considerably.

When to Call Quality Comfort

If basic checks don't solve the problem, or if your furnace repeatedly locks out, it's time for professional heating repair. Our technicians handle all furnace brands and types across Asheville and WNC. We carry ignitors, flame sensors, pressure switches, and other common parts on our trucks for fast repairs.