Surely someone can fix it at reasonable cost. It would be a shame to have the ducting and cabling in place with no aircon.
Our flat had the ducting and cabling in place (2 beds, kitchen, lounge) but the first owner had decided to cut cost and not pay for the equipment installation.
It cost us 2000E to have, medium quality, quiet, Toshiba units put in. But for asthetic reasons in your case I would probably be prepared to pay as much as a cheap external system (400E?) to have the old system repaired and serviced.