Unusual noises from an air conditioner can be caused by something simple (like a loose panel or dirty filter) or something that needs service (like a failing fan motor). Use the steps below to safely identify the most common causes.

Before You Start: Safety First

• Turn the AC off and wait a few minutes.
• If you’ll be checking anything inside the unit, unplug it (or turn off the breaker for central systems).
• If you smell burning, see smoke, or hear sparking/crackling, stop and contact a professional.

Step 1: Identify the Type of Noise

Different sounds usually point to different causes:

• Rattling / Vibrating: loose screws, loose front panel, unit not level, debris
• Buzzing / Humming: electrical issue, loose wiring, failing capacitor, fan motor strain
• Clicking: normal relay/start clicks (sometimes), thermostat cycling, loose parts
• Squealing / High-pitched screech: belt/motor issues (more common in older systems), fan motor bearings
• Grinding / Metal-on-metal: fan or motor damage (service recommended)
• Gurgling / Hissing: refrigerant flow (some is normal), airflow restriction, possible refrigerant leak (service recommended)
• Banging / Thumping: fan hitting something, loose blower wheel, debris in outdoor unit

Step 2: Quick Fixes You Can Do at Home

A) Check the Air Filter (Most Common)

• A clogged filter can make the system work harder and create whistling, humming, or rattling sounds.
• Turn the unit off.
• Remove the filter.
• Clean or replace it (follow the filter arrow for airflow direction).
• Turn the unit back on and listen for improvement.
• Tip: Replace/clean filters regularly, especially during heavy use.

B) Make Sure the Unit Is Stable and Level

• A unit that shifts during operation can vibrate loudly.
• Window AC: confirm it’s seated firmly in the window and supported properly.
• Portable AC: make sure it’s on a flat surface and the exhaust hose isn’t kinked.
• Outdoor condenser (central/mini-split): ensure the pad/bracket is stable.

C) Inspect for Loose Panels or Screws

• Rattling often comes from a loose cover.
• Turn the unit off.
• Gently press on the front cover/panels to see if the noise changes.
• Tighten any accessible screws (do not overtighten).

D) Look for Debris or Obstructions

• Leaves, dust, or small objects can cause clicking, rattling, or grinding.
• Window/portable units: check the front intake area for objects.
• Outdoor units: remove visible debris around the outside (keep at least 2 feet of clearance).

E) Check the Fan (When Safe)

• If you hear a repeating tapping or scraping, the fan may be hitting something.
• Turn off/unplug the unit.
• Look for obvious obstructions near the fan area (don’t force anything).
• If you see damaged blades or the fan appears off-center, stop and contact service.

Step 3: Reset the Unit

• A quick reset can clear minor control issues that cause repeated clicking or odd cycling.
• Unplug the AC (or turn off the breaker) for 5 minutes.
• Plug it back in (for plug units, press TEST then RESET on the plug if present).
• Turn the unit on and test.

When to Contact TCL Support

Stop troubleshooting and contact TCL Support for the following:

• Grinding, screeching, or metal-on-metal sounds
• Buzzing that continues and the unit won’t start or keeps shutting off
• Electrical burning smell, smoke, or sparking
• Hissing along with poor cooling (possible refrigerant issue)
• The noise is getting worse over time or the unit is vibrating violently

Helpful Tips to Prevent Noise

• Keep filters clean.
• Keep the area around the unit clear of dust/debris.
• Ensure the unit is stable and properly installed.
• Don’t run the unit with blocked vents or a kinked exhaust hose (portable ACs).