Why Is My Gas Furnace Making a Clicking Noise and Giving Me No Heat?

Most likely, your furnace's spark igniter is trying to ignite the burners or pilot light but is unable. This is a simple ignition system failure - but until it's repaired, you won't be able to use your furnace. The easy fix to this problem is to call your local HVAC repair person, who can repair or replace the ignition system easily.

What to Know About Your Furnace Ignition System

When you turn on your thermostat, your furnace turns on and an induced draft fan motor turns on, thus pulling air into the burner. The ignition system turns on, and then ignites the furnace burners. These burners heat the air, which is then pushed through the HVAC system by the furnace blower. This is how warm air is distributed throughout your home.

If the ignition system malfunctions, the burners can't light.

Why Do I Hear a Clicking Noise?

Most likely, your furnace operates with a spark igniter, which is similar to the igniter that you might see on a gas stove. There are two types of ignition systems that your furnace could use:

• Direct spark ignition (DSI): This system uses a spark igniter to directly light the burners in your furnace.
• Intermittent pilot ignition: This system uses a spark igniter to light the pilot. The pilot then lights the burners.

Regardless of what type of ignition system your furnace uses, this explains why you're hearing a clicking. The "spark" is happening, but it isn't lighting the pilot or burners.

There are multiple potential problems that your furnace could be having.

Problem With Pilot Light

Problem With Thermocouple

The thermocouple is a flame sensor that opens the gas valves that lead to the furnace burners. Thermocouples can malfunction if they're broken or if they're just too covered in soot to sense the pilot flame. The igniter will click for a minute trying to ignite the flame before stopping.

Problem with the Gas Valve

Gas is a requirement to ignite your furnace. If the gas valve remains shut, maybe because it's malfunctioning, then the spark igniter will click without igniting anything. There are multiple problems that could be occurring to make the gas valve malfunction, including a bad valve, a bad ignition board or a bad connection between the two.

Either Way, You're Going to Need Help from a Pro

Most likely, if your ignition system is having a problem, it's not going to go away on its own. It's time to solve the problem! If your furnace is not igniting, contact an HVAC professional today. Tell them your furnace clicks but doesn't turn on - they'll know exactly what you mean.