When I was warming up the truck this morning, 36F, I smelled a wood fire but it wasn't the neighbors' fireplace. It was in the cab.

Now the blower motor only works on high speed. I bet the resistor pack for the fan motor just fried, perhaps due to a bunch of Texas oak leaves in there.

Anybody have a diagram of how to pull that resistor pack? Is access under the hood or under the dash?

 

Access is under the hood, a few inches inboard of the blower motor:

https://www.ford-trucks.com/forums/1...n-the-cab.html


Heating, Ventilation, & Air Conditioning - ???Gary's Garagemahal

 

Mine was so full of debris I can't believe it didn't catch fire!

 

Thank you. My son has the truck at school today. I'll have to look tonight, in the dark.

 

I got the resistor pack out, tight access, years of greasy dust, real fun. Leaves were in there all right. But the resistors look fine. What doesn't look fine is the oxidized triple connector at the lower end. Needed lots of cleaning and conductive copper grease.

I was gazing upon our progress with chilly dark evening satisfaction in the glow of my LED baseball cap, when I noticed that the heater core hoses are looped back to the firewall....all this work and the fan resistors will work now but deliver NO HEAT tomorrow morning, because the PO apparently disconnected a leaking heater core.

What is the collective wisdom of the forum regarding heater core R&R? Is there a good source for reasonable prices who sponsors the forum, or should I find a good local radiator shop to fix it?

 

Replace that blower resistor and clean out the airbox. It can start a fire if there's crap in there.

Don't waste time or money with the cheap China aluminum heater cores to replace the failed original. I went through at least 3 of those in a short time and swapped to a Motorcraft copper heater core. It was around $70 from RockAuto, no more problems. Original lasted 30 years, this one should too.

 

I didn't have any problems with my replacement heater core from the store, but that was years ago, they may have changed. I have seen people get on here once in awhile and complain the ones you get in the store sometimes don't fit exactly right.

If you do not have factory A/C, I would try to get the best core you can, those are difficult to replace. If you have A/C, it's right behind the glovebox, is not too bad to replace, so if you wanted to roll the dice on one it would not be too bad to pull it out again.

 

Thanks for the tips. I need to pull that resister again and ohm test it. It looks fine but this morning I still only have high speed. And yes, we removed the leaves last night. But now I need a heater core too so I plan to do a more thorough cleaning then.

 

Look at the resistor assembly again, see if it has a little round silver thing that looks like a capacitor on it. If it does, that can burn out, it's a thermal link like they put in coffee makers.

I don't know when Ford started putting those things in there, the older cars didn't have the thermal links. You can try radio shack for a new one, or I have just bypassed mine before. Or go buy a new resistor assembly.

 

>little round silver thang

Yep! I got that. So it's like a 1-time thermal fuse? I'll test that little bad boy tomorrow.

 

That's exactly what it is, a onetime thermal fuse.

 

Resolution

I jumpered that thermal link with 12g copper wire. Soldering it was heck, had to break out a little propane soldering iron to get it hot enough to stick.

Then as I was putting it back in, it occurred to me that the resistors heat up as they do their job. I had a doubt...would all that heat just melt my soldering job? Erk...

Well, that was a week ago and she's still holding up. So nice to have four fan speeds again! Thanks to all for the help.

 

So, um, how much do you want for your tailgate when you part out the truck after the fire? Luckily I don't need anything near the source of the fire, but am looking for a good tailgate and maybe some exterior trim pieces. What's forum protocol for a situation like this? Should we make requests in this thread, or go with an entirely new post-fire part-out thread?

All seriousness aside, Ford put that thermal limiter there for a very good reason. The fact that older vehicles didn't have one is immaterial. Ford identified a problem. Amazingly, the lawyers convinced the bean counters to spend the extra money in production to address the hazard. That's how you know it's important.

Roughly $23 for a new resistor pack with thermal limiter:

https://www.rockauto.com/en/catalog/...+resistor,6557

Any parts store should have one sitting on the shelf.

I'd hate to see yet another urban legend involving a pickup and the bypassing of an electrical safety device:

https://www.discovery.com/tv-shows/m...-fuse-minimyth

 

Help me understand. It's in a fiberglass housing, with the AC evaporator next to it. What can burn, other than leaves? I'm installing SS screen over those grates. Does that fiberglass burn?

Thanks for the supplier lead btw. 1A doesn't offer that part. I tried.

 

The same Ford that didn't fix Pinto fuel tanks. Musta changed liars.