What HVAC Noises Mean and When to Worry

Noise Guide

• Banging — loose or broken part inside the blower. Turn off and call a tech.
• Squealing — belt slipping or motor bearings failing. Needs lubrication or replacement.
• Clicking at startup — normal for ignition. Continuous clicking means igniter or relay failure.
• Rattling — loose screws, duct vibration, or debris in the unit.
• Humming — usually normal. Loud humming from the outdoor unit could mean a failing contactor or capacitor.

When to Turn Off the System

Any grinding, screeching, or burning smell means turn it off immediately and call for service.

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