AC Making Strange Noises

What buzzing, rattling, grinding and other unusual AC sounds may indicate.

Start with safe, simple checks

Confirm the thermostat setting, check whether the system has power, and inspect an accessible return-air filter if you know how to do so safely. Do not bypass safety controls, open sealed equipment, handle refrigerant components or work on energized electrical parts.

What the symptom can tell you

This symptom can have more than one cause. Airflow restrictions, controls, drainage, electrical components, equipment condition and other system issues can produce overlapping signs. A symptom alone is not enough to diagnose a specific failed part.

When to request HVAC service

Call when basic checks do not restore normal operation, the symptom returns, comfort is deteriorating, or you see water where it could damage the home. For burning odors, smoke, sparking or another immediate safety concern, stop using the equipment when safe to do so and seek appropriate emergency help.

Continue troubleshooting

See the common AC problems hub, or go directly to AC repair when the system needs professional attention.