Loud rattling, buzzing, or vibration noise from the indoor unit during operation.

Safety first: Turn off power before touching the unit.

Steps:

• Check mounting: Gently push on the indoor wall bracket and unit. Tighten wall bracket screws if the unit moves.
• Inspect blower: Remove the front cover and look for debris in the blower wheel. Remove any foreign objects.
• Secure panels: Ensure the front cover and filter access panels are fully latched and not vibrating.

If noise persists: The blower wheel may be unbalanced or the fan motor bearings worn. Replacement of the blower wheel or indoor fan motor may be required.