Key switch does not kill blower motor

[Goliath38]

My 1987 325is has a new problem. When I turn the ignition off the a/c fan blower motor keeps running unless I turn it off manually. I am thinking that a relay has gone bad but don't know which one. There is now a constant drain on the battrery even with the fan motor switch turned off. Any suggestions appreciated.

[shogun]

You need the wiring drawings of that car, otherwise difficult to find the relay or whatever causes the problem.
Or pull one fuse after the other till the blower stops, and then see what is all connected to that fuse.
In any case a Bentley Repair Manual for your car should be on your X-mas present / wish list.