HVAC Making Clicking Sounds: What Different Noises Mean

HVAC systems make various sounds during normal operation. Understanding what clicking means helps you know when to be concerned.

Normal Clicking Sounds

Startup and Shutdown A few clicks when the system starts or stops is normal. This is relays engaging and components cycling.

Thermostat Relay The clicking sound when your thermostat calls for heating or cooling is the relay activating.

Metal Expansion Ductwork expanding and contracting with temperature changes can produce clicking or popping sounds.

Concerning Clicking Sounds

Rapid Repeated Clicking (No Start) If you hear rapid clicking but the system doesn't start, the capacitor may be failing. The system is trying to start but can't get enough power.

Clicking from Outdoor Unit (Compressor Not Running) The contactor may be engaging but the compressor isn't starting. This could indicate compressor or capacitor problems.

Clicking During Operation Clicking while the system runs could indicate: - Loose parts - Failing bearings - Object in the fan - Electrical issues

Clicking and System Shutting Off If clicking precedes unexpected shutdown, a safety is triggering repeatedly.

What to Do

For Normal Clicking No action needed. These sounds are part of operation.

For Concerning Clicking - Note when it occurs (startup, operation, shutdown) - Whether the system is functioning normally otherwise - Any patterns (every cycle, intermittent)

This information helps technicians diagnose the issue.

Call for Service If - System won't start despite clicking - Clicking is new or has changed - Other symptoms accompany the clicking