OK I was confused by the "hang on the wall" part and assumed a mini/split. In a regular AC unit with separate line voltage feed I agree you need a disco. In fact, these may have a pretty hefty toaster wire heat strip in them. My condenser is something like 17a, the air handler is closer to 50 with the heat on. (10 kva heat), on a 60a circuit.
Since these usually get installed in the attic or in a closet there is always the argument about working clearance around the disco. For some reason they usually let that slide but get concerned about the one on the condenser. Never made sense to me.
