Amazon Smart Thermostat Relay or Power Circuit Noise

Thermostat emits a buzzing or clicking noise during operation

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Mechanical relay chatter due to low voltage, Loose wall plate causing vibration, Failing internal relay

How to Fix / Troubleshooting

Safety: Turn off HVAC power at the breaker before reseating the thermostat.

  • Reseat thermostat: Remove and firmly snap the thermostat back onto the wall plate to eliminate mechanical play.
  • Check voltage: Have a technician verify that the 24V supply is stable and within spec; low voltage can cause relay chatter.
  • Observe pattern: If buzzing occurs only when switching modes, it may be normal brief relay operation. Continuous or loud buzzing suggests a failing relay.

Persistent loud buzzing usually indicates internal relay failure; replace the thermostat.

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Repair Difficulty

Medium 3/5

Required Part

Amazon Smart Thermostat Main Control Assembly
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