Dave Freeh

I have a 79 911SC that melts the Air Conditioning fuse body, not the fusible link itself. The new style fuses are plastic, not ceramic. The plastic deforms without blowing the fuse. I think that the bimetallic switch/evaporator blower resistor is shot.
Has anyone else had this issue?

wwest

The problem is the fuse holder itsself. Over time and temperatrue, HEATING due to current, especially HIGH SURGE current flow, the fuse holder loses its "springiness", ability to clamp the fuse TIGHTLY. That results in milliohms of resistance between the fuse and holder, fuse clamp, and therefore localized heating right at the point of fuse/holder contact.

In my case, '78 SC Targa, the phenolic material, backing plate, supporting the fuel pump fuse clamp burned away and the fuel pump failed at the very worse of times.

A good ~50,000 mile maintainance procedure is to remove all of the fuses and then use a tool, needle-nose pliers, to (carefully) bend/tighten the fuse clamps so the fuse is HELD more tightly. It doesn't hurt to "grease" the fuse clamp contact area with the electrians grease often used on alluminum wire "scotch lok" twist contacts.

I initally developed that procedure on the 5 volt HIGH current backplane fuses of a Data General Nova/2 minicomputer.

Dave Freeh

Thanks for the insight. I didn't occur to me that so much heat can be produced by a lose connection. I will make the adjustment that you suggest.