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Why is My HVAC System Making a Rattling Noise?

Rattling Sounds and Other Sensory Signs Your HVAC Needs TLC

When your HVAC system is operating as it should, you probably don’t notice it much. There might be an initial click when it turns on and the starting hum of the fan, but then it likely fades into the background noise. You rely upon your senses to notice when your HVAC unit seems different: a strange sound, an unfamiliar smell, or even the feeling that it’s warmer or cooler than normal. Oftentimes, new and unusual sounds are the early warning signs from your HVAC unit that all is not well. Investigate and address rattling, clunking, or grinding sounds before it’s too late. 

In this post, we’ll focus on rattling sounds coming from your HVAC and some probable causes.

Shake, Rattle, and Roll: Causes of HVAC Rattling Sounds

Loose Hardware: There’s a good chance the rattling sound you hear coming from your unit is a loose screw. Screws securing your condenser or evaporator are subject to vibration. Over time, the vibration can loosen screws, creating a rattling sound. For this problem, the solution is very simple: just tighten.

Nearby Debris: Residential HVAC units are usually located outside a home where grass, dirt, and sticks can get in through the housing and become stuck. Commercial HVAC units in lots or on roofs can suck in pebbles and other tiny pieces of debris, too. The rattling sound could be debris knocking around in the HVAC components. For this problem, the simple solution is to remove the housing and clear all debris.

Fan Alignment: If the fan of your HVAC unit is misaligned, the vibration of the fan could cause it to knock and clank against the HVAC housing. This is not as common, but it could be the result of a poor installation or lodged debris affecting the balance of the fan. If it’s debris and left unchecked, it could cause the fan to seize and create a bigger problem. If you address it early, it’s an easy fix.

Motor Troubles: This is the most major of the causes. If parts of the motor are loose or coming apart, you may first notice it as a rattling sound. If you inspect the motor thoroughly, you may find it’s just a loose screw or debris, but if left unchecked, there is the potential for more serious motor trouble.

Hearing Strange Sounds? Call Harbin!

We’ve got our fingers crossed that it’s just a screw we need to tighten, but take comfort in knowing that if it is a more serious problem, that fixing it early is always easier and cheaper than waiting until the problem compounds.

If you hear a rattling sound coming from your HVAC, give us a call. We’ll inspect your HVAC unit for the common causes above first.

To speak with a Harbin Heating and Air technician about your unit’s rattling, contact us today!