The SECOP/DANFOSS Control modules are mounted on the side of the compressor, and everything is wired into the terminals. We sometimes call this the "black box"!
There is a DC only module (used on many systems as well as ASU models), and AC/DC module - this one has an AC converter built into it to transform AC power to DC for the compressor, and the BD80 compressor.
Please note: you cannot use an AC/DC module on a system with the ASU control. It creates conflicts with the electronics.
ASU modules are Red for air-cooled, and Blue for water cooled, and the White module is for for the ASU systems using the BD80 compressor.
The Voltage Reducer is for the pump on a water-cooled system.