AC Troubleshooting
AC Making Noise? What Different Sounds Mean
Updated January 2026 • 5 min read
Your AC shouldn't be making weird noises. Different sounds indicate different problems—some minor, some that need immediate attention.
AC Noise Guide
🔴 Grinding or Screeching
Urgency: High - Turn off and call
Metal-on-metal sounds indicate motor bearings are failing or a fan blade is hitting something. Running it can cause more damage.
🔴 Banging or Clanking
Urgency: High - Turn off and call
Usually indicates a loose or broken part inside the compressor or a disconnected fan blade. Don't run the system.
🟡 Buzzing
Urgency: Medium - Schedule service soon
Can indicate electrical issues (loose wires, failing contactor), refrigerant leaks, or debris in outdoor unit. Get it checked before it becomes bigger.
🟡 Clicking (Repeated)
Urgency: Medium - Schedule service
Repeated clicking when trying to start suggests a failing capacitor or relay. Normal to hear one click at startup, but continuous clicking is a problem.
🟢 Hissing or Bubbling
Urgency: Low-Medium
Some hissing is normal. Loud hissing or bubbling from refrigerant lines can indicate a leak. Get it checked.
🟢 Rattling
Urgency: Low - Check yourself first
Often just loose debris (leaves, sticks) in outdoor unit, or loose panels/screws. Check and clear debris. If it persists, call for service.
When to Shut Off Your AC
Turn off your system immediately if you hear:
- Grinding or screeching sounds
- Loud banging or clanking
- Continuous clicking (not just at startup)
- Any sound accompanied by burning smell
AC Making Strange Noises?
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