Need, one of the neutral wire is connected to the chiller from power source. The controller sits in between the live wire from power source to chiller.
Do note you need to provide power to the controller, which means you need to have a live and neutral to the controller's power input as well.
The controller just acts as a switch on the line where you placed your chiller and power source.
I mod and tested mine, works brilliantly. Will post pictures real soon, maybe tomorrow.Mine is controlling both chiller and a fan, which acts as exhaust fan for chiller.
Let me know your brand and model of controller, I will post you a step by step.