Noises and Smells From Your HVAC System

While some HVAC noises and smells might be harmless, others require professional help.

September 28, 2022

A man experiences smells from his home HVAC system.

Sometimes unpleasant smells and noises coming from an HVAC unit can indicate a problem with the system that could require maintenance or repair. If you’re experiencing air conditioner noise or if your air conditioner smells a bit funny, there may an issue inside your system. Components that could experience these problems include:

Compressor – While compressors are noisy by nature, if your compressor is making loud or unusual noises, it may be worn out.
Drive Shaft or Fan Blower Motor – If the drive motor is making loud noises, it may need some lubrication. All motors need to be lubricated at all times, otherwise it will wear out. Loud noises may be either situation.
Fan Blade – If one of the fan blades break off, it can start rubbing against the house and cause unwanted noise.

If the air from your system smells musty, it may be due to mold and/or mildew build up in your duct system. One way to get rid of this is to change the filter and clean the drip pan in your HVAC system. Clean using bleach or white vinegar to make sure the area is no longer hospitable to mold growth.

Common furnace noises and their causes

There are several furnace noises listed below, some of which could indicate a problem with the unit. If you’re concerned about a furnace noise contact your local American Standard dealer to schedule an HVAC check-up:

Screech – This could be a problem with your motor or fan belt.
Chirp – Chirping sounds are fairly common with furnaces and usually the natural noise of the mechanisms.
Rattle – Rattling noises typically happen when the system is cooling down and is not usually cause for alarm.
Boom – When the weather outside warms up or cools down, the ductwork in your house expands and contracts. If this happens and your furnace smells like it’s burning, you might have a dirty burner in your furnace or a defective gas valve.
Ping – This sound can also be caused by contracting and expanding ducts.
Hum – When the furnace burner lights, it may cause a humming sound.
Whine – Whining or odd vibrating noise may indicate a problem with your furnace.
Crackle – Crackling noises may be the metal parts cooling down after the furnace shuts off.
Clunk – Clunking or bumping sounds often means you have a cracked belt.

The best way to determine whether your furnace is making an odd sound is to learn what it sounds like during normal operation and note any changes in the type or volume of sound as the unit ages. If you notice a significant change, call your local American Standard Heating & Air Conditioning Dealer to schedule an inspection.

Professional help for unwanted HVAC noises and smells

If you’re experiencing unwanted noises or smells from your HVAC system, call a professional. While some noises are normal, others could indicate that something is wrong with your system. An American Standard Customer Care dealer can come to your home to see what may be wrong with your HVAC system and repair it, allowing your family to enjoy some comfort, peace and quiet.