The only thing that draws much current through the Klima relay is the AC compressor clutch. Check for a shorted coil or worn wire that touches something.
Clutch can be replaced without venting the AC, I think. Probably a huge PITA, but better than converting to 135a if you still have R12.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!