Inspection of the refrigeration unit has yielded it's dead.
Corrosion ate through the piping at the lowest points, allowing the freon and lubricant to escape. When the compressor was powered it hummed angrily and the ammeter took off so it's rightfully seized.
Good news is that instead of hacksawing the lines so I can at least salvage the evaporator which is a rather specific fit to the machine there are threaded couplings I can loosen to separate it from the dead assembly. Leaves hope that int he future a new compressor and evaporator can be found.