I have a walk in cooler I wired, needed a 3phase 20 amp line to the compressor, draws 12 amps, and it needed a 20 240v line to the fan coil unit. The fan coil unit draws 3.3 when the fans are on and 12.5 when the defrost coil is on.
The refridge guy was questioning my bill as he thinks 1 circuit would have done it all. Now I know the compressor draw and the fan draw would not overload the breaker but taping of the 3 phase line for single phase sounded odd to me and something I would never think to do. He says they do it all the time and most electricians don't know how to wire the refridgeration stuff. Anyone have input on this? Thanks.

Is this a packaged unit with a nameplate? Possibly, a 3 phase sub-panel, and then run from there 2 0r 3 ckts. This way you have a good source. There's no main control box, where a feed is brought to?

Not a packaged unit.
The 3 phase feed hits a disco then the compressor
The single phase hits a defrost clock then the fan unit.
They are mounted about 15ft apart.