Sorry for the all caps in the subject line, tried to edit but I couldn't change it... Didn't mean to come across as shouting.
After studying both system schematics (my head still hurts!) I have managed to complete the swap. I am no electrician by any means.
As mentioned previously, when attempting this swap, cut the manual hvac box from the main harness to the left of the unit, as well as the smaller harness to the left and behind the floor ducts. Don't remove any wiring from the manual box itself.
There are only about three wires to splice in the cabin. Grab power from the existing blower (redwire) and ground from the "geblasereglar" (blower regulator) located on the passenger side behind the glovebox. You rejoin the bigger and smaller harness wires back together from the manual box (they match in color)
In a previous write up the "geblasereglar" and "tempereglar" (tempurature regulator) boxes were referred to as a radio amplifier. I believe this is not correct.
The third wire comes from the temp wheel and is for the A/C clutch switch. I located the wiring from the A/C relay and spliced in near there.
In the 240D the A/C Clutch switch and Aux Fan relays are connected (pin 3 to pin 4). On the 84 300d they are not. I cut pin 3 from the A/c clutch relay and spliced into pin 4 wire of the Aux Fan relay. Forgive my electrical ignorance in terminology... I was afraid to cut pin 4 wire as I noticed from the schematic that both relays would not have 12v switch source? -Need help with this... Would any electrical gurus know how to activate each relay with a switch??? I'm not confident in my wiring here. I sheared my pressure port in the A/C line tightening the 134a adapter fitting, so a/c test will have to wait in meantime.
As far as I can tell, you do not need to do anything with the harnesses that plugged into the CC head unit or tempurature regulator.
Another observation is I only have the highest blower setting. 1 and 2 do nothing, bad blower resistors?
Hope this helps
