Thermostat emits a faint buzzing or clicking noise during operation.

Safety first: Turn off power before removing the thermostat from the wall.

• Step 1 – Identify source: Listen closely to determine if the noise comes from the thermostat or from the boiler/air handler.
• Step 2 – Check mounting: Ensure the thermostat is firmly attached to the wall base and the base is securely fixed to the wall to reduce resonance.
• Step 3 – Reduce cycling: Adjust control settings to reduce rapid on/off switching that can cause frequent relay clicks.
• Step 4 – Replace if excessive: If the relay or transformer buzz is loud or continuous, the component may be failing. Replace the thermostat module.