Fan fused melted but didnt pop (PIX)

posjr

Registered User
I have done the fan wire trick so fan is always on. Than the other day i overheated. Turns out my fan was off. checked fuse and found this! Whats wierd is the fuse didnt pop. Even some of the houseing melted and the pin raised up when i took the fuse out. Now i'm worried the wires my be melted aswhile. And now need to replace the fuse box! I had a 60amp fuse.


Going to just relay the fan to the battery.

Any ideal why this happened.

EDIT: Was just thinking. I have a FMIC and wounder if the fan was working overtime trying to pull air! Fan still works. The IC is about 2inchs away from the A/C and raditior.
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    251.3 KB · Views: 181
Last edited:
Like Dave says - it happens to most 94/95 models that have the fan fuses in the underhood box, versus a separate fusible link (89-93). When mine fried I by-passed the fuse carrier and installed a new fusible link powered off the threaded buss on the side of the fuse box. Fortunately the melted fuse didn't spread beyond it's slot in the box, so I just filled the hole with rtv.
 
What that is telling you is the fan motor is drawing much too much current to operate and should be replaced. Most likely the stator shaft bearings are shot and creating drag.

The draw likely built up as the fan ran, thus it didn't pop the fuse, but it did heat things up enough to melt things.
 
Due to the fact that I've seen this condition on every 94/5 SC I've ever looked at (including pristine low mileage ones) I think it is due to a defect in design. I don't feel that a push-in style fuse makes good enough contact for the load it carries. On circuits that continually carry high current a different style fuse should be used that uses screws or bolts to make the connection tight. The SC uses this on other connections but not the fan circuit.

The heat is caused by resistance of the connection, not heat in the entire circuit. If it were heat in the entire circuit you'd see other melted points as well which I have not seen. It's always just the fuse connection itself.
 
If you ever looked at a time vs current curve for a fuse it's easy to understand why this happens. Fuses are designed to protect against short circuits which are very high current fast acting events. Fuses are not designed to protect against overloads which are relatively low current but long time events. A 60a fuse will operate at 65a for almost an infinite amount of time, it may overheat but it will not clear. That same fuse will clear a 1000a event in a few micro seconds.
 
If you ever looked at a time vs current curve for a fuse it's easy to understand why this happens. Fuses are designed to protect against short circuits which are very high current fast acting events. Fuses are not designed to protect against overloads which are relatively low current but long time events. A 60a fuse will operate at 65a for almost an infinite amount of time, it may overheat but it will not clear. That same fuse will clear a 1000a event in a few micro seconds.

Makes good sense.

The fan spins smooth. So tonight i'm going to add a relay with a 60amp fuse and some 8 guage wire.
 
add +1 to melted fan fuse + box on a 94/95 sc..my fan shut off at the track.. thought it was ICRM then just suddenly said HMM MAYBE THAT FUSE MELTED, went and check... meltedddd and the little pin moves around now..

whats the best fix for this ?
 
Last edited:
I had the same problem on my 94 SC a few years back but it was the fan wiring harness connection that was partially melted. I cleaned it up best I could, plugged it back in and it's been working OK every since. I checked the fuse in the high current fuse box and it looked alright at the time. I guess I better check again on both my SC's.
 
+1 for melted fuse. Mine was so burned I had to get the pliers out and rip the fuse out, it was nice and brown but the fuse was still good inside.
 
Looks like those cheap parts from japan stike again. I had trouble with both my 94`s with the inside fuse box as the fuses did not fit snug and did not make contact with the blade of the fuse on better than 10 amp circuits. The contactors inside were thin and cheap. Lots of burned blades on non poped fuses. As for the fan I feel that when you cut a wire to keep your fan running all the time it over heats right at the fuse and the connector in the fuse expands and then starts arcing buning up what ever is next to it. I feel the fault is the fuse itself and keeping your fan on will make it go south quick. Here is a 40 amp I took apart. Talk about cheap. If you replace the fuse every couple of years you should be alright.
P.S. if you add a relay now you will need to worry about that failing as well.
 

Attachments

  • pic`s.jpg
    pic`s.jpg
    48.7 KB · Views: 84
Last edited:
that happened in my 90 too. the fan seized and melted all the wires but didnt pop the fuse. now i have it on a switch casue its such a mess.
 
They used a fusable link form 89-93. Just a smaller wire that will burn up if a high load or short should accur. Only 94-95 had the cheap fuse.:rolleyes:
 
Back
Top