This article applies to the ecobee3, ecobee3 lite, and ecobee4
A clicking noise indicates that the voltage is insufficient between the RC and C terminals. This can sometimes be due to a bad C wire or a C wire that is not properly connected at the HVAC equipment side.
Consider the following:
- If you repurposed a spare wire you found behind the wall to use as a C wire, please ensure that wire also connects to the C terminal or C connection point at your HVAC equipment
- Try using another wire in place of the C wire, ensuring it is connected to C at both the ecobee and the HVAC equipment
If your C wire is bad and you are unable to repurpose another wire as C without sacrificing one of your HVAC system's functions, you may need to install the Power Extender Kit or run additional wires.