Write up with pictures, aux fuse for blower motor
 

Thanks Jeremy, you were right, it is pretty easy.

The FSM, section 54-180 calls it "separate fuse for blower motor". My car is an 86 300SDL, ending number 267785. My other SDL (recently sold) already had this kit installed and the ending number is 277550.

This was a work around for a problem of the blower motor fuse, # 16 in the fuse box melting the plastic to a point where contact was lost. I don't know what all vehicles had this problem besides 86 SDLs with a low ending number.

The kit consist of a 30 amp strip fuse in a small fuse box. There are two leads about 14 inches long for making connections under the main fuse box at #16 attaching screws.

My concern was getting under the fuse box. I see these large wire harness bundles going into the box and wondered how I would ever get enough slack to raise the fuse holders. Well, it turns out the large bundles stop at the wall and the small individual wires provide plenty of flexibility to raise the fuse holder assembly.

Here goes, with the battery disconnected and the box lid removed, unsnap and remove the grommet block cap, (see pic). The snaps are vertical, one on each end. I used my thumb.. Remove two philip head screws that are out of site among the spare fuse holders. I got fooled at first and removed two hex head (8mm) screws outside the box. The screw holes look just like a spare fuse holders..

I have dial-up so I'll do three posts, if I can get pictures to load.

Thanks
Harry

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This problem also affects the W123 240D and 300D. It's agravated by melting cheap plastic aftermarket replacement fuses. So if your blower fuseholder is still intact, make sure you use the OE ceramic fuse there.

Happy Motoring, Mark

With the screws out and the grommet cap off, I used a small screwdriver to pry the fuse holder up from the box. I then used a rope to hold it up. There is a clip connection on each side between the fuse holder and the relay holder, I unsnapped each side and that provided a pivot that allowed more height for the fuse holder without raising the relay holder .

It was then easy to access the #16 screws and connect the leads from the aux. fuse kit.

I made a deviation from the FSM with the outlet wire. The book seems to indicate these two wires are connected in a junction box. What I did was stack them and connect with the original screw. The FSM calls for that procedure for the inlet wire. I intend to cut off the old up top # 16 fuse holders and fill that void with shoe goo.

So, what I did was remove the outlet screw, slide the blk/grn eyelet on the screw and reinstall it. I did the same with pink/grn wire for the inlet side.

The next post will explain routing of the wires.

Thanks
Harry

The SDL has a firewall a few inches forward of the fuse box and there is a grommet box with spare openings to install new wires. The FSM indicates the aux. fuse kit installation remain on the fuse box side of the firewall. I elected to leave my aux. fuse on the engine side of the firewall the same as what Jeremy did. Its easier to check the fuse.

So I took both wires through the firewall grommet and the fuse box grommet. Its neat that the fuse box grommet blocks just slide in and out, makes it real easy to push the wires through, then slide it back in place. The picture shows it removed and back in place. That grommet cap I removed at the beginning holds these blocks in place.

I plan to ziplock my aux.fuse box to something just forward of the firewall and I'll add pictures when its done.

Thanks
Harry

Mike, Thanks for identifing the additional vehicles.

X2 on ceramic fuse base with copper fuse metal. The fuse box itself is what melted on mine. I assume the ever present fuse spring pressure, combined with the excess heat, pushed the inlet fuse contact far enough into the soft fuse box to prevent a good enough connection to power the blower.

Thanks
Harry

That is exactly what happened to my '87. The PO then installed an aftermarket external fuse and I upgraded that to the factory fuseholder kit.

Because the external 30 Amp strip fuse is aluminum, I advise coating its contact surfaces (where it screws to the holder) with anti-oxidant. The stuff that electricians use when they join aluminum and copper wires is ideal. You need very little, just a thin coat to prevent electrolytic corrosion.

Jeremy

Will do, I use DeoxIT and that should do the trick. I think I'll also do my 80 amp glow plug fuse, seems like that would be the same situation.

Thanks
Harry

Agreed, the only difference is that the preglow relay is used for a few seconds at a time while the climate control blower may be on for hours. A poor electrical connection has resistance and gets warm, which makes the connection even worse causing it to get hotter and hotter until something melts.

Last of the write up
 

It was easy going back together. While I was there I replaced all the fuses with ceramic/copper and made sure of proper sizes. I treated each end of each fuse with DeoxIT.

I am not satisfied with the aux. fuse box mounting. I like the way Jeremy has his, but my car is different. Hmmm, got to think awhile.

mines been done at the dealer all ready long time ago :)

I've noticed that the OE fuses in my Mercedes, as well as Mercedes, BMWs & Volvos at my local Pick-N-Pull, are ceramic, but have aluminum strips. I suspect that also contributes, over time, to deterioration and excessive heating at the copper fusebox contacts.
Ironically, many of the plastic, aftermarket fuses have brass or copper strips, so I've started scavenging those to rewire my blown OE ceramic fuses, at least for high-drain items like the heater-blower.

Otherwise, on my 240D, I was able to pry the blower's inner fuse contact out of the melted fusebox plastic, and clean both contacts sufficiently to not have further problems, so far with a ceramic fuse. But lately, I'm not driving that car so much either.

Alternately, I was able to pull the fusebox, and transfer the blower wires to a vacant, undamaged set of contacts in a friend's '83 300D. So far it's also been working OK - with a ceramic fuse.

Happy Motoring, Mark