The fuse (25amp)on my 1986 300E melted it's socket (#12) in the main fuse block. The fuse did not blow, but the pressure fronm the upper retaining spring pushed the lower contact through the melted plastic until it no longer makes contact. The contacts do not appear to be too corroded to cause this type of resistance, but the motor does draw a bit of current. I have since purchased a replacement fuse box, but in the mean time have connected a remote fuse using the original contacts under the fuse box. The line is rated at 30 amps and I have a 25 amp fuse in it. If I run the blower on high, this fuse still gets very hot to the touch. I am not sure if I want to install a new fuse block and have another melt down.
The motor was replaced by the PO and still under warranty, so I replaced the motor with a new Bosch unit. It didn't cost me anything, eliminated a possibility and was a good learning experience.
I see that later cars had a remote fuse at 30 amps near the strut tower. Is this a problem with earlier cars, hence the change, or should I continue to search out why my fuse is getting hot?