The wiring diagram can be found within the installation manual for the Guardian EC, available on reznor.co.uk
Surface Mounted Air Curtains Reznor Guardian EC
Recessed Air Curtain Reznor Guardian EC
Air Curtain Wiring Diagram - Guardian-EC-Wiring-Diagram.pdf
Control Panel Wiring Diagram - Intelligent-Control-Panel-Wiring-Diagram.pdf