Good news, and not a moment too soon to enjoy those toasty summer days. Was it the KLIMA relay you're talking about, p/n 002-545-13-05, that took care of it? If so, the EPC doesn't show any change in part num for your car, so I can't imagine why the pin layout would be different. When the OVP underwent a pin change (5-pin, then 7 then 9), each of those was given a new p/n. That's odd. Are you certain you got the correct relay?

I'm still studying your first photo in post #9 to try to understand what the non-standard wiring and components are all about. Does the low fan speed stay on all the time that key is on? If that's what's happening, that could have been accomplished much more easily than by wiring up two new components that don't belong there (the ones closest to the left inner fender). The other thing that puzzles me, is what are the two wire leads coming off the harness that were originally connected to the red hi-pressure switch now connected to? Anything? And what's up with the yellow wire? Is it connected to anything? I think I'd want to pull out the non-standard components and return the circuit to its original design, but that's just me. Anyway, nice job, and a nice looking 260E, and only 82K on the odo. Wow!

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't