Heater blower motor and power window circuit blowing fuses where to look next...
 

I am having an issue with my 92 w250 LE, I replaced the fusible link in the harness that goes to the blower motor power window circuit, I replaced it with an inline fuse. It keeps blowing,(lighting up the water in fuel lights and wait to start light) even if I have the blower motor on low and never any higher than that. What should I look at next, how do I know if its the blower motor drawing too much amperage? Resistor? bad ground?

THanks in advance

I don't know if replacing a fusible link with a fuse will actually work well. I think the fusible link will carry allot more amps. It certainly sounds like you've got something drawing more than it should though.

This was happening on our 92, and the wires right where they go into the ignition switch in the column, were melted and touching each other. which I think fried the ignition switch, or vise versa.

I would replace the ignition switch in the column (NOT the key cylinder), you'll need some #20 Security Torx bits.

Also inspect the wiring going up the column, mainly the pink wire.

If it was working before you replaced the fusible link, I would look again at your wiring. Sounds like a short to ground.
Cheers

unplug the blower and see if it stops and what size fuse are you using in place of the link?

OK I will check out the ignition switch wiring, I replaced the fusible link with a 15A fuse and a 20A fuse, they only lasted about 15 or 20 mins each. I believe that fusible link is a 20 gauge wire which is worth about 8 amps, so i was already above what i think its supposed to be with those fuses.

oh and it was not working before replacing the fusible link, the link blew so I replaced it with inline fuse, several other links have recently blown, the one that runs the dash and ignition circuit, and one other one that I havent found what that goes to yet, i replaced those with inline fuses and they haven't blown yet just the window/blower motor one.

I dont know if this is related or not but my stereo works intermittently too.

Fusible links are designed to blow, so they run way hot. It'll be 40 amps (Orange 20g link)

You should replace it with a 40 amp slow blow fuse.

Odds are good it's all related. You'll find a chaffed harness somewhere, or shorts in the ignition switch.

Attachment 59189

thanks for the info so far guys, I did take apart the steering column covers and looked at the physical part of the wires and nothing is jumping out at me that looks out of the ordinary (no melted insulation, smells, or chaffed wires) I looked from the firewall all the way up the column to the switch plug in.

On another note, I did unplug the blower motor itself and it has not blown the fuse yet. It would normally blow it when I have selected heat, or vent, etc on the hvac controller.

Anything I should try next guys? thanks in advance

A new blower motor if nothing in that circuit jumps out at you. With that said, hows the airflow out of the vents? Maybe the box is in need of cleaning too.

Actually to update this again, I did have the fuse blow finally, still with the blower motor unhooked. I will check the blower motor box, although it seems pretty forceful when its on, not really weak at all. So does this rule out the blower motor itself?

I just want to rule things out one at a time?

If it was unplugged and the fuel blew then the problem is not in the blower motor. Get a mulitmeter and ohm from the fuse to ground, it should read open or OL or OLH, different meters say different things, but you need to see nothing. If there is something then you need to start seperating circuits to find the short. Try to duplicate what is happening to the truck when it blows, like if it blows when you hit a big bump then start shaking the harnesses and see if the meter changes.
My harness for the driver door had a short in it where it goes from body to door, not saying that is your problem, but look at places like that, where the harness is moving and has potential to pinch or break wire insulation causing a short.

ok thanks for the advice, I have been noticing a pattern that usually when starting the truck, is when the fuse blows, Ill have to check all that wiring

Turned out to be the ignition switch guys thanks

The switch itself or the pigtail? Either way glad that's over with huh?