HY M8NC

Driving around just now, and noticed the temperature gauge was pretty high. I went over to a friends shop and opened the hood. Only the driver side fan was running-even with the a/c on.

A check of the connection showed no juice to the fan-so we think relay. When I got to the fuse block-I noticed the blown fan fuse. I replaced this fuse last week, and it appeared to be original. I replaced it with a new "Glass tube" type of fuse-same 16a. It didn't fit snug in the holder, but fit o.k.

What could be blowing this fuse? Does the glass fuse being loose cause a resistance that would cause it to fail? I have replaced it this time with the correct type of factory plug-does anybody have any thoughts?

RobbyK

I have this same problem, in fact it’s in the shop for it now. If you changed the radio or one of the connections from the stock radio came lose it will come in contact with metal in the back of console and cause the fuse to blow least that what happened with mine, and if its not that it is most likely another ground some where on you car is touching metal. I also had the same new type fuses and replaced both fuse banks with them and only the radiator fan /radio antenna would blow so it is probably not the fuse its self.

IceShark

If the fuse is not connected solidly some strange/bad things can happen. The resistance at the poor connection point will heat way up (especially with the current that fan draws) without first blowing the fuse. Finally things get hot enough to melt whatever is around and melt the fuse element, ending the crisis. Some of those fuse elements can take over 700*F to melt!

One of my headlight kit guys had this happen and the rubber fuse holder was charred and smoking before the whole plastic blade fuse finally melted in half. There was no damage to the attached wires just the loose fuse acting like a minature toaster oven.

HY M8NC

So, you think it's because of the fuse being loose, Ice-
That's what I'm thinking, but you are kind of the electrical Guru...
Thanks for the confirmation.

944togo

Also had the same problem on my 84 944. Kept blowing fan fuses, and I tried all the different types. Brought it to a Porsche shop, and they couldn't figure it out and gave me some wrong information. Finally went to an auto electrical shop (highly recommend "Capital Auto Electric," in Pompano Beach, FL.), and they knew right away what it was and did a permanent fix. Seems the fuse box itself was bad, and they simply bypassed the stock fuse box and wired in two new fuse connectors that use the new type fuses just for the fans. Haven't had a problem since.
The rest of the fuse box seems to be alright and all the other fuses were left in place, just had to rig up a bypass for the fans only. Capital said this was a common problem on these cars.

amxess