Even in Southern California, we rely on furnaces during chillier months. All furnaces make occasional noises. Sometimes those noises act as quiet background noise and comfort us when we sleep.

But, what about those furnace noises that sound different or suspicious? Certain furnace noises need immediate attention.

Keep reading to learn more about common furnace noises that you shouldn’t ignore.

Normal Furnace Noises

You will notice some noise when you first turn on your furnace. Common furnace sounds are a pop or click as the furnace heats up. The furnace often settles into a dull hum.

The hum and click are often louder in older furnaces compared to newer ones. Annual tune-ups ensure your furnace will continue to run smoothly during colder California months.

Furnace Noises You Shouldn’t Ignore

If your furnace is making noises that seem out of character, it can be a sign that your furnace needs repair.

Be aware of these noises that you should always pay attention to.

Loud Bang

If you hear a loud bang or pop come from your furnace, it is often the result of dirty burners. Gas builds up because dirty burners are difficult to ignite. When the burners eventually ignite, a loud bang occurs.

This sound is concerning because the situation could eventually cause a small explosion. It could also crack the heat exchanger which would require an expensive repair.


If a part has come loose or becomes worn out, you will often hear a squealing or whining sound.

A common issue is a loose blower belt or damaged blower motor. Other times, your furnace will squeal if the shaft bearings need lubricating.

Seek out maintenance right away if you hear squealing. Ignoring the problem will cause additional damage.

Loud Humming

Although dull humming is normal in most furnaces, be aware of loud humming. Older furnaces may have a louder transformer that causes the humming.

But, if the humming seems out of character, you may need to replace the fan or capacitor.


If you hear repeated clicking when you turn on your furnace, it could be one of many issues. It could be an issue with the thermostat. This is not a complicated issue to fix, but it should still be addressed with a technician.

A clicking noise can also indicate a broken flame sensor. There could also be a disconnect between the gas and the ignition.

Sometimes, a repeated clicking noise indicates a problem with the capacitor or fan.


A persistent rattling noise can indicate broken parts in the fan or motor. Sometimes, rattling sounds come from loose screws on the front panel. If this is the case, you can listen to figure out where the rattling is coming from.

Screws could also need tightening in the ductwork. Be sure to address rattling sounds right away. If the noise worsens, it could indicate a complete system failure.

Let Us Fix Your Furnace Problems

If you hear any of these concerning furnace noises, be sure to call Comfort Now for maintenance. Our skilled technicians will accurately diagnose and fix your problem.

Are you located near Tulare, Visalia, or Hanford, California? Contact us today to schedule your furnace tune-up!