If you just connect 12 V to the blower you will get maximum speed and no control.

You can put a rheostat but remember that you will dissipate a lot of heat doing this.

Not very easy to do.

What is wrong with your controls that is making you want to do this?

Which car, 80 300TD with the ACCII (evil servo) or 85 300D with the ACCIII?

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech