Why Does My Furnace Keep Clicking?

It's cold outside, and the furnace kicks on like normal—well, except for that strange sound. "Why does my furnace keep clicking?" is a common question from homeowners. And while there's no such thing as a completely silent furnace, clicking isn't a noise you want to hear, especially if it's a gas furnace.

Furnace Clicking Causes

Worried about a constant or intermittent clicking coming from your furnace? There are several possible sources. Here are six of the most common reasons your furnace is making a clicking noise:

1. Faulty Gas Valve
   Does the clicking happen at irregular intervals? If so, a faulty gas valve may be the reason. The gas valve feeds fuel to the pilot light and burner. A broken valve cannot regulate how much gas reaches the heating components. The pilot light may try to ignite repeatedly, causing the much-dreaded furnace to click sound. Is the gas valve your culprit? A faulty gas valve is more than just a nuisance; it's an emergency. Too much fuel may build up inside your system, resulting in a dangerous gas leak. This situation is a job for professionals. Turn off your furnace and gas supply, and call your local HVAC expert immediately.
2. Failing Flame Sensor
   Near the rear of your furnace is the flame sensor. This often-overlooked device plays a major role—it detects the presence or absence of a burner flame. If there isn't a flame, the sensor will shut off the system. However, if the flame sensor is dirty or corroded, it won't be able to do its job, and you may hear a clicking sound instead. Is the flame sensor causing the clicking noise? Shut off your furnace and look at the flame sensor. If there's residue on the rod, clean the sensor with an emery pad.
3. Ignitor Problems
   The ignitor keeps the pilot light burning. When the thermostat calls for heat, a series of events triggers the ignition system. If the ignitor fails, the gas valve won't open, and the burners won't light. Instead, the furnace will keep trying to start the ignitor, and you'll hear a clicking sound instead. Is the ignitor to blame? If the furnace is making a clicking noise and won't turn on, you may have a failing ignition system.
4. Loose Draft Inducer Fan
   Inside your furnace is a draft inducer fan. This fan plays two roles. First, it clears out any leftover gases at the start of a cycle. Second, it fuels the burners with constant oxygen. Over time, the blades may wear out. You may hear a clicking sound before or during a cycle. Could it be the fan? If your furnace clicks but still comes on normally, the inducer fan may be loose or dirty. A good cleaning and calibration should resolve the problem.
5. Blocked Blower Bearings
   Bearings keep the blower running smoothly. Just like any other furnace component, however, they can wear out. Dirt, dust, and debris may block the bearings, and when this happens, odd noises are common. Are bad bearings your issue? If the furnace starts clicking but still heats normally, rusty or corroded bearings are a likely problem. Lubricating sticking parts and replacing any worn-out bearings should stop the clicking.
6. Cracked Ductwork
   A home's ductwork circulates air. Heated air flows through the ducts into the different rooms of your home. It's uncommon to hear air as it moves through the vents, but cracks or loose ductwork may make clicking or popping sounds. Are cracked ducts the source of your problem? If your furnace still runs, but you hear clicking near the air vents, damaged ductwork could be the reason.

Strange Noises? It's Time to Schedule Professional Service

Suspect there's something wrong with your gas furnace? Odd noises, strange smells, and irregular cycles could point to a bigger issue. It's a good idea to contact your local Aire Serv^® immediately to rule out emergency problems, like a gas leak. Our technicians will inspect your furnace from top to bottom, providing you with peace of mind. Connect with us online or call us to request furnace repair services.