Common Types of HVAC Noises and Their Causes

Common Types of HVAC Noises and Their Causes

Have you ever heard a strange noise coming from your HVAC unit and wondered what caused it? There are many different noises that can come from an HVAC system. It’s important to identify them in order to determine what may be causing the noise, as well as how severe of a problem it may pose.

The HVAC system is one of the most important elements of home comfort. It keeps us warm in the winter and cools in the summer. The HVAC system also makes some noises that we can’t ignore. These noises are telling us something about our systems, whether we want to hear it or not.

Also check: How to Maintain Your HVAC System During the Winter

Types of HVAC Noises and Their Causes

There are two different types of HVAC system noises: sounds that indicate malfunction and sounds that are normal. Before you start hunting for a solution to your HVAC noise, you need to determine if it’s normal or not.

1) Banging Noise:

Common Types of HVAC Noises and Their Causes

If your HVAC is making a banging noise, this is an indicator of a problem with the compressor. The compressor is what pumps refrigerant into your air handler, which in turn cools and heats your home. A loud banging noise can be an indication of a break in the coil, which is a pipe that gets extremely hot and transfers the heat from inside the house to the outside. If a broken coil is not replaced immediately, you may find that your HVAC unit no longer works at all.

2) Screeching Noise:

Common Types of HVAC Noises and Their Causes

Screeching or squealing noise from the HVAC system can be a warning sign of the HVAC components reaching the end of their useful lives. A screeching sound commonly indicates that your fan motor bearings are wearing out and in need of repair. A squealing sound may be due to a bad bearing, but it can also result from a fan blade rubbing against the fan housing or another part of the HVAC unit.

3) Humming Noise:

Common Types of HVAC Noises and Their Causes

The hum from the HVAC unit can be annoying, especially if you live in a building that has a lot of noise. It’s often difficult to pinpoint where the humming is coming from. If you have an older unit, there’s a good chance it’s worn out and needs to be replaced.

If your HVAC unit starts making noise for no reason, it could mean something is wrong. The problem could be as minor as a blockage or loose piece of metal, or something serious like an electrical issue.

If your HVAC is not making noise when you turn it off, then there might be a problem with the contactor relay switch. This is an easy problem to fix.

First, check the wires that connect to the switch. Make sure that they are tight and in the right place. If they are not in the right place, you need to move them before proceeding.

4) Rattling Noise:

Common Types of HVAC Noises and Their Causes

The rattling noise coming from your outdoor unit can be caused by loose dirt, leaves, sticks, or other foreign objects inside the unit. Remove any loose dirt or debris on the outdoor unit fins. This will eliminate the rattling sound and also help prevent dirt from entering the unit and damaging it.

The rattling noise is also caused by a short that may be caused by any of the following:

  1. Broken or loose wire
  2. Loose terminal connection
  3. Bad capacitor
  4. Loose coil or fan blade
  5. Bad transformer or motor

5) Clicking Noise:

Common Types of HVAC Noises and Their Causes

If you hear clicking noises from your HVAC system, it may be indicative of a thermostat malfunction. The clicking noise can be heard when the furnace is turning on or off. The clicking sound may be caused by the relay that shifts from low to high voltage and vice versa.

A clicking sound from the thermostat means that the temperature sensor is unable to register a temperature change due to either a short circuit or obstruction in its path. The sensor for the furnace is either faulty or covered in dust and needs replacement.



In this article, we have discussed the most common types of HVAC noises and their causes. Understanding the different noises your HVAC system makes can help you identify what’s wrong and potentially save you a lot of money down the road. If you are experiencing any of these noises in your home, be sure to call a professional for help.

K2 Mechanical specializes in providing residential, and commercial Heating, Ventilation, and Air Conditioning repair for customers throughout Long Island. To learn more about our services and what we can do for you, please visit our website today!

Common Types of HVAC Noises and Their Causes


About Author

Gulzar Abid

Gulzar Abid

Gulzar Abid is a passionate entrepreneur with a thirst for knowledge and yearns to help empower people to initiate their journey of growth and success. Chief Executive Officer K2 Groups Chief Executive Officer K2 Heating & Air Conditioning

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