What’s that clicking sound? We get a lot of complaints from homeowners about strange noises coming from their furnace. The sound might be a symptom of a number of HVAC problems. Find out how to identify the issue and fix it.

It’s normal for a furnace to make a clicking noise when it’s first turned on. This is the sound of your ignition starting. If you notice that the clicking sound continues, however this could indicate a serious problem with your HVAC system. If your furnace isn’t working, won’t turn on, won’t stay on, and isn’t heating, you surely want to fix the problem ASAP. Sometimes it’s a symptom of a faulty flame sensor, a bad connection with the ignition, or leaky gas valve.

Why Is Your Furnace Clicking?

Look below for the description of what your furnace is experiencing. We’ve provided some helpful information to understand what’s going on in there.

Furnace Clicking, But Heat Is Working Normally – Bearings

If the heating system seems to be working fine except for the noise, there is one common causes. Bearings in the inducer blower or the main furnace blower may be the source of the clicking. Loud clicking sounds can be heard when inducer blowers and fan shafts are clogged by buildup or when bearings are worn out.

Bearings on the main blower motor might click as the furnace runs because the shaft is rusted or dirty. Cleaning and lubricating the fan shaft will help fix the problem and prevent premature wear. Sometimes blower motors begin to click as they wear out. Worn out bearings can cause the motor to burn out if not replaced in time. This is a good sign that your HVAC system is ready for a maintenance call and possibly replacement of that part.

Furnace Clicking, But Heat Is Working Normally – Inducer

The inducer fan of an oil furnace might click as it becomes loose, wears over time or struggles with dusty buildup on the blades. An HVAC tech can quickly clean and calibrate the inducer and resolve the problem.

Furnace Clicking, But Not Turning On – Flame Sensor

Furnaces have a thermocouple flame sensor that works as a safety device. The thermocouple is likely reacting to an abnormal flame temperature and shutting off the gas automatically. This is why the clicking sound continues.

If you furnace begins clicking and the blower turns on and off again, this may indicate a faulty flame sensor. Professional heating system services can clean, repair or replace the flame sensor.

Furnace Clicking, But Not Turning On – Pilot Light

As your furnace runs, day after day and year after year, the pilot light assembly may become loose, wear out or get clogged. Clicking noises may indicate that the pilot light is not functioning correctly. This is a serious problem but it’s usually an easy one for an HVAC tech to fix.

Furnace Clicking, But Not Turning On – Ignitor

If your furnace continues to click and won’t turn on, it may be an indication of a problem with the ignitor. Like a gas stove, the furnace should click when it fires up. If it keeps clicking and not igniting, however, you need to have a certified HVAC tech look at it. The issue could be loose wiring or a damaged or clogged ignitor.

Leave the repair work to the professionals. A small mistake here could be dangerous, causing a gas leak or fire.

Furnace Clicking, But Not Turning On – Gas Supply

Ongoing clicking when the furnace isn’t working may be a sign that gas isn’t reaching the pilot light. The ignitor will keep clicking as it tries to spark a flame. This could indicate a dangerous gas leak or clogged gas valve.

Irregular clicking sounds coming from the gas valve could also be a sign of insufficient voltage. This might be caused by faulty gas meter controls or the thermostat controls. If a gas furnace runs and then shuts off, or short cycles, this indicates an inconsistent flow of gas. An electrician should test the voltage at the gas meter, thermostat controls and the gas valve to locate the source of the problem. If the gas meter needs replacing, the work will have to be done by a gas company technician.

HVAC issues involving the gas supply are serious and possibly life-threatening. Call an HVAC professional for assistance.

Furnace Running Normally, But Ducts Are Clicking – Ductwork

Some homeowners notice clicking or popping noises in other parts of the house or at the air vents. This is usually an indication of loose or cracked ductwork.

What Are Other Furnace Noises You Shouldn’t Ignore?

Your HVAC system might be trying to communicate with you. Here are some noisy signs of a furnace problem.


Various buzzing noises could communicate a loose transformer component in the furnace.


If the HVAC filter is dirty and clogged, you may notice a whistling sound coming from the system. By replacing the furnace filter about every 90 days, you will help your heating system to run more quietly, work efficiently, and run cleaner.


This annoying sound may be telling you that a belt or the fan motor is wearing down.


The noise of metal scraping against metal often indicates a problem with the blower wheel. It may be hitting another furnace part, or it might have come loose or be damaged.


Continual rattling noises are often symptoms of broken fan or motor parts.


It’s normal for a furnace to make a sound that sounds like birds when it’s first started up after sitting for an extended period. Loud chirping, however, may be telling you that the inducer blower is clogged, a bearing is worn out, or a belt needs to be replaced.

Get more expert advice here: What’s Better for a Pennsylvania Winter: An Electric Furnace, Gas Furnace or Ductless Heating and Calculate.

Time to Call in an HVAC Professional?

Regular HVAC maintenance is the best preventative medicine for furnaces. But if you’re hearing some strange sounds coming from your heating system, it’s probably time for a more extensive intervention. Whenever you see or hear anything unusual about your HVAC unit and how it functions, you should call in the professionals.

To schedule maintenance or repair services by a certified technician, call AQM at (610) 363-3940 or request a quote online.

AQM, Inc.