Air conditioners aren't silent, but unusual sounds often indicate problems. Here's what different sounds mean.
Normal Sounds - Gentle humming when running - Clicking when starting/stopping - Slight whoosh of airflow - Occasional water dripping
Concerning Sounds
Banging or Clanking **Possible causes:** - Loose part in compressor - Disconnected components - Motor issue
Action: Turn off system, call for service
Screeching or Squealing **Possible causes:** - Belt slipping (older units) - Motor bearing failure - Fan blade issue
Action: Investigate promptly
Buzzing **Possible causes:** - Electrical issues - Loose parts - Refrigerant leak - Compressor beginning to fail
Action: Have inspected
Clicking (continuous) **Possible causes:** - Relay problem - Thermostat issue - Electrical issue
Action: If continuous, needs attention
Hissing **Possible causes:** - Refrigerant leak - Duct leak - Compressor valve issue
Action: Schedule service, especially if cooling is affected
Rattling **Possible causes:** - Loose panels or screws - Debris in unit - Motor mounts
Action: Often easy to fix, but investigate
When to Act
Turn off immediately: - Loud banging from compressor - Grinding sounds - Burning smell with any sound
Schedule service soon: - New sounds that persist - Sounds getting worse - Sound accompanied by performance issues
Can wait a bit: - Minor rattling - Slight buzz that doesn't change - Normal operational sounds
Regular maintenance can prevent many sound-related issues. Strange sounds are your AC asking for help—don't ignore them.