bernard farquart

I have had an issue that recently began in my '84. My heater blower motor fuse actually melts the plastic body of the fuse, but the electrical connection part of the fuse does not blow.

The first one, I thought perhaps I had a faulty fuse, but then my replacement fuse melted to the point where the fuse was too short to make contact, but it never blew either fuse.

Fuse gets HOT upon reinstall, but does not blow.

No other effected circuits, so I am not thinking the usual ground issues, just the one.

Fan works great when a new fuse is installed, no other issues.

Any ideas?

Imo000

Are the cheap Chinese fuses?

928mac

I think!, but I am not sure,
that if you have high resistance (loose connection) on the load side spade and not the bat side, it may cause it to over heat and melt.

Just a guess

smiffypr

A slightly bad connection at either side of fuse will slightly limit the current and generate lots of heat. You need to clean the fuse holder and possibly bend the contacts in to better grip the fuse.

M. Requin

And what Imre said- check the source of the fuses, the Chinese fuses are notorious for problems like this.

Leon Speed

BTDT. Upon inspection there was an some metal from the previous fuse in the fuse holder, causing poor contact. Cleaned the fuse holder with fine grit sanding paper (fold over a few times) until shiney and no more problems since then.

WallyP

Heat at the fuse is always poor contact on one or both fuse contacts. Usually between the fuse and its connectors, but sometimes between the connectors between the fuse holder and wires behind the panel.

bernard farquart

I'll clean the contacts, hopefully that's it. I had the fuse panel out once before, that was enough.

Thanks for the ideas

kary4th

The crappy name brand (Busmann sp?) fuses you can get at auto stores/walmart are made from plastic. Mine melted regularly. I found a seller on eBay with "European fuses.". They're reasonably priced - come in blister packs if maybe 16 or 20. Best of all, the ones I found are ceramic, just like the originals in my '78.

smiffypr

The plastic ones are probably safer. In the case of the ceramic ones, you can have a bad contact, generate lots of heat without the fuse showing any sign. In the case of the plastic one the fuse melts and ceases to push on the contacts and the circuit is broken forcing you to investigate before the heat causes a fire.
Just a theory.

blown 87

I have seen the plastic bullet fuses melt away at both ends, and still pass current, just stuck to the prongs of the fuse holder.

Alan

Bussman is actually a premium brand - ATO/ATC fuses are supposed to be made of plastic - it is not a sign of poor quality. Bussman & Littlefuse are the 2 ATC brands I recommend. For the Barrel style fuses (<85) The plastic should be quite fine - though the originals were ceramic. What matters most are the dimensions, metallic composition, plating & fuse element accuracy. If the fuse gets hot enough to melt the plastic you have a bigger problem which you should solve...

Chinese no brand name ATC fuses are often made with poor fuse accuracy, poor materials/plating (including the plastic compounds) and even incorrect blade thickness/dimensions - these fuses cause problems (heating) due to poor connections and may damage the fuseholders permanantly... I assume similar is true of Chinese barrel fuses...

Alan

bernard farquart

I got a bunch of Bussman fuses from my work, when I pulled out my fuse panel, and they were the wrong length. They were all too long, and I could just barely make them work. I was very unhappy with the quality control they showed.

The red one on the left is a new, improper length fuse.

GlenL

I've had this happen. As it heats and softens it loses contact and gets even hotter. It could fall out and into another fuse. Not good.

Use good, ceramic fuses and give them a spin once or twice a year.

kary4th

Yeah, I know. Bussman is the name brand out there. The point of the fuse is that it does, will and is supposed to get hot. Really hot. Hot enough for the metal to burn and break the circuit when necessary. If the plastic melts first, umm, the fuse is a dangerous piece of crap.

Just saying.