Here is my delima, on my 87 300 SDL, I just finished changing the blower motor and 30 AMP fuse and nothing. I'm suspecting the blower regulator. Based on all the threads sounds like with the age of the car and the fact that the blower motor was probably drawing more current it blew the blower regulator. I did notice something else. When I had the temperature control on max heat and any setting, bi-level, defogger, etc.., I noticed that the compressor was running. Rather odd isn't it for the compressor to be on when the setting is on heat? Could the problem be with the climate control unit and not the blower regulator. Anyone have any thoughts?

the comp will run when yer system calls for heat. at max heat does the
blower work? if so then most likely its the regulator. but check the pushbutton unit for solder cracks in the circuit board.

george