What Those AC Noises Mean: A Troubleshooting Guide

Your air conditioner communicates through sounds. Understanding what different noises mean helps you know when to address issues before they become expensive repairs.

Normal Sounds

• Some sounds are perfectly normal:
• Gentle humming when running
• Soft clicking at startup and shutdown
• Quiet whooshing of air through vents

Sounds That Need Attention

Banging or Clanking **What it means:** A loose or broken part inside the compressor, or a disconnected component. **Urgency:** High. Turn off the system and call for service to prevent further damage.

Squealing or Screeching **What it means:** Belt issues (in older systems) or motor bearing problems. **Urgency:** Moderate to high. Schedule service soon to avoid a breakdown.

Buzzing **What it means:** Electrical issues, loose parts, or debris in the unit. **Urgency:** Moderate. Have it inspected during your next service call.

Clicking (Continuous) **What it means:** A failing thermostat or defective control. **Urgency:** Moderate. May affect system operation.

Hissing **What it means:** Refrigerant leak or compressor issues. **Urgency:** High. Refrigerant leaks reduce cooling efficiency and can damage the compressor.

Grinding **What it means:** Motor problems requiring immediate attention. **Urgency:** Very high. Turn off the system immediately and call for emergency service.

When to Call a Professional

While some sounds are harmless, err on the side of caution. Strange noises often indicate small problems that become major repairs if ignored.

If you hear any unusual sounds, document when they occur and what you're hearing. This information helps technicians diagnose the issue more quickly.