I'd let my truck sit for a while.. well I was storing it at my Grandads house. Anyway, went and got it the other day and noticed when I was running the heat there was a sound like the blower fan hitting against something I figure its probably a leaf stem or something but I didn't think anything of it and drove it about 1.5 hours back to my place and parked it again.

Today I get in it and start it up, and while I'm waiting for it to heat up smoke starts coming out from under the dash and the vents.. and through the big hole in the top of the dash where I guess a speaker used to be. So I shut it off real fast and grab my extinguisher and pop the hood.. but nothing under the hood looks unusual.. there's still smoke coming from the dash though so I fire the extinguisher down the big hole a bit and up under the dash on the passenger side too just for good measure (figured I'd rather clean up the powder mess than burn the truck down) and then just shut the doors and watched it for a while. Well the smoke stopped and its not burned down yet so I guess the fires out.

The question is (after I tried to research a bit on here) is it likely that it was the resistor coils igniting some debris that got blown in by the fan or could something else have started it burning .. the smoke smelled like burning leaves so I don't really think it was electrical.

Oh yeah, can anyone give me an idea on just where that resistor/blower motor is on an 86 with a 302? I'm going to have to pull the dash apart to clean out all the extinguisher powder anyway but if theres any advice anyone can give about the situation I'd be really grateful.

Thanks =)

sorry so long winded

 

Resistor and blower fan are under the hood typically, air or not.


High output heater



Standard output with air



Resistor should be located in the air stream next to the blower motor. In the first diagram, it is pictured, but not labeled at the lower right of the blower motor.

 

Ahh I see it there. Thanks.. so I guess the leaves and what-not (mouse nest?) is gonna be jammed in there between the resistor and the core... its gotta be mice right?.. how else would debris get all the way back in there to the resistor.

 

The opening to the fan for fresh air is open to the slots in the rain gutter, so leaves and crap get in there all the time. It could be a mouse as well, but this kind of thing happens a lot. On some occasions, it has caused major damage.

 

Thanks again.. I can't wait to dig into this and see just what happened in there.. I'll bet thats never been cleaned out. but its gonna have to wait till warmer weather =(

Actually I just had another question, I'd like to be able to move it into the driveway to work on it (when I get around to it) reckon it would catch up again if the heat and blower was turned off.. or maybe i can just pull the fuse for it?

 

If you unplug it at the fan, it should be fine, or just simply turn it all the way off, again should be fine. the resistor can only get hot if electrical current flows through it. You can also just unplug the resistor. Two screws and the resistor is out.

 

I just had the same thing happen on my 86 F350. Smelled like a brush fire, that diagram is great thanks for putting it up.

 

Happened to me once. I had to abandon the vehicle until the smoke cleared, My fire wasn't caused by the resistor. Mine was the heater core got hot and the leaves and crap started to smolder. The truck stunk for weeks!

 

I got a free F150 truck once due to the burning junk on the resistor! The PO shot over 4 fire extinguishers in the dash(which did more dammage than the fire itself). TO clean up that mess I hosed it out after taking out the seat ,floor mat, radio and cluster and any other electronic thing that hates water.

 

I cleaned mine out a few years ago and found a leaf stuck to the resistor, a fistful of leaves in the heater box, and handfuls of leaves inside both kick panels. I removed the cowl panel and found more leaves, acorns, a Snickers bar candy wrapper, and a butter knife.

Ford addressed this problem in 1987 with the redesign of the F-Series trucks. The cowl panel grille was changed from the slots to small holes. The small holes eliminates the chance of leaves and acorns etc. from getting in.

If you wish, you may swap your present cowl panel for a 1987 - 1991 cowl panel. It is a direct swap and the body lines of the newer cowl panel match up to the hood lines on the 1980 - 1986 F-Series exactly.

 

My 81 sat out in the woods for about 2yrs. I had mice in the tailpipe, air cleaner and the heater /air box was filled with leaves and pine needles. I took the blower resistor assy off the air box, taped a piece of heater hose to my shop vac hose and cleaned it out through the resistor hole. Anything too big to get sucked through the hose stuck to it .It might not hurt to give it a little shot of air freshener after.

The blower motor resisters I've seen, mostly older truck, have the nichrome wire resistor right out in the open and it could start a fire if leaves etc. get in the box.

 

I had exactly the same experience as Lariat 85 did. I made custom covers for the cowl
vents when it is parked so I won't have the problems again. I'm looking for an 87-91 cowl to put on it when I have it repainted.

 

Thanks for all the ideas and sharing experiences and such.. haven't got a chance to look at it yet due to work though =/ Glad I only shot about half of a small extinguisher in there hehe might get away with getting the shop vac out.. looks like from the diagram that the powder probably never even made it all the way to where the fire was.. well better safe than sorry I guess.

I was wondering just what the resistor even does.. besides letting you know that your heating system is full of leaves =) I just can't figure out why its got to be there.. reckon I'll go try and read up on that.

 

Ok .. I read and learned what it does.. but still dunno why its gotta be where it is.. unless it really is a flammable debris detector

 

lol, neither of those pics show the blower motor resistor.