Loud humming, buzzing, or knocking noise from the outdoor unit during operation.

Safety: Turn off power at the breaker before touching the outdoor unit. Moving parts and high voltage are present.

Steps:

• 1. Inspect fan blade: Check for cracks, missing pieces, or loose mounting on the motor shaft. Tighten the fan blade nut or set screw if loose.
• 2. Check for debris: Remove leaves, branches, or other objects that may contact the fan blade.
• 3. Tighten panels: Tighten all screws on the outdoor unit panels and grille. Loose panels can vibrate loudly.
• 4. Check mounting feet: Ensure the unit is level and that rubber feet or pads are intact. Add anti-vibration pads if necessary.
• 5. Compressor noise: If the noise is a deep hum or knocking from the compressor body, this may indicate internal wear. This requires professional evaluation and possible compressor replacement.