Why is My Air Conditioner Making a Rattling Noise?

  1. Man listening with hand by ear

If your air conditioning system is especially noisy, it might be trying to tell you something. Unfortunately, loud rattling noises typically mean something is out of whack with your AC system and a repair is needed.

Aside from the sound of your air conditioner starting and stopping a cycle, cooling systems are relatively quiet, so any unusual or loud noise should be a cause for concern. In our most recent blog, the heating and cooling technicians at Mission Mechanical focus on one noise in particular – rattling. We’ll discuss what this sound means and what to do to fix the issue.

The heating and air conditioning technicians at Mission Mechanical have served homeowners and business owners across the Indianapolis area since 2002 and take pride in offering exceptional air conditioner repair services, whether the issue is short cycling, low airflow, or, as we’ll discuss below, an annoying rattling sound.

What Causes an Air Conditioning Unit to Make a Rattling Noise?

Rattling can be caused by a number of issues and is a sign your air conditioner may be on the verge of a breakdown. You should contact a qualified HVAC company such as Mission Mechanical immediately to inspect and repair the issue.

Here are some of the most common causes of a rattling air conditioning system.


Your outdoor AC unit can receive quite a beating during the summer, as it’s exposed to the elements and debris. Sticks, leaves, small branches, rocks and other debris can fall through the cracks of your AC condenser unit, especially during storms, causing the unit to make a rattling sound.

We recommend contacting a professional HVAC company to clean out the unit. A certified HVAC technician can carefully dislodge any debris without causing damage to crucial parts. If left unchecked, debris can damage system components, leading to air conditioning repairs.

Misaligned fan

If your outdoor air conditioner’s fan becomes misaligned and loose, it can hit the casing and cause a rattling sound, which can lead to extensive repairs. The cause of a misaligned fan can include debris that knocks the fan out of place, wear and tear and improper installation. Contact an HVAC company to make the appropriate repairs to the unit and stop the rattling noise.

Loose panels or screws

Another issue to look out for that can cause an air conditioner to rattle is loose screws or a loose panel. If screws are loose or fall out of place, causing the panel to become loose, it can create rattling. This usually occurs when the AC unit is beginning to deteriorate, signaling that it may be time to consider replacing the unit altogether.

Damaged motors

If one of your outside AC’s motors starts to break down, such as the blower motor, it can cause other internal parts to become loose, causing rattling. Contact a heating and cooling pro right away to repair a damaged motor on your air conditioner, as further damage can occur the longer the issue is left unattended.

Contact Mission Mechanical for Air Conditioning System Repair Services

We all know how hot and humid summers in Central Indiana can get, making a properly functioning air conditioning system a necessity. If you’re experiencing any AC unit issues, such as a rattling condenser that’s keeping you awake at night, don’t hesitate to contact the HVAC system professionals at Mission Mechanical to schedule an appointment.