If your Air conditioner is not an armstrong unit the mystery wires are for the Air conditioner thermostat. If you look closely you will find a hole in the wall above the credenza and may find the screw holes that were made when the thermostat was mounted.
As to the original hook up to 12 VDC in 77 I don't belive there was a referigerator made that was auto ignition, let alone had a circut board to control stuff. So tere would have been no 12 VDC there as factory wiring. You could always tap into the 12 volt feed to the antenna/tv outlet on the wall in the lounge??
