I have the same problem. Is the resistor in the same location on an 09?

 

I can't speak directly to an '09, but it's always been in the same place (in the fan plenum) on every thing I've ever seen from Ford.

 

I've seen a fair number of these in the several months since I first came to this post, and I have seen a lot of melted plugs, corroded contacts, broken resistor wires, and etc. To date, I have not seen or heard of any fires cause by this proble. So, I decided to experiment.

I took one of the old, melted plugs that I had left over from a repair. I made a wire support in a vice, and applied a low flame from a propane torch to it. The plastic first melted, then charred, with minimal flame. As soon as I removed the torch flame, though, the plastic stopped burning (it smoked a bit, and stunk - a lot!) Apparently they selected a non-flammable plastic for this application - and wisely so, too!

So, I imagine the chance of a fire starting from a similar problem is remote. However, if you ever happen to smell a really nasty chemical burning odor while you're driving along, this is probably a really good place to look!

 

Not sure that the cause is the same in the trucks, however I had an early 90s Escort with the very same type of issue. Come to find out the cause is due to debris build up under the windshield wiper couling that cause water to backup and over top the heater system intake that is located under the coul. The only fix I ofund was to make sure and clean the debris out regularly (the maple seeds have a wonderful way of blocking up the coul area drainage).

 

So what part do you replace?

 

My blower only works on high, but i dont have heat at all. The resistor only causes the other 3 speeds not to work right? or does it make the heat not work either? and i took mine out, i dont have a melted plug, the resistor is corroded but no parts are melted or broken off.

 

The resistor only controls fan speeds, not the heat itself. If you're not getting heat at all, you might want to check the switch and/or control panel. It's probable that the vacuum operated doors aren't working probably. You should be able to hear them move when you operate the heat control from "OFF" to "FLOOR". If not, there's a problem with the vacuum system somewhere, and you'll have to trace it down.

As far as the blower only working on one speed, check the resistor carefully, and also check it with an ohmmeter to make sure the element doesn't have a break in the resistance wire somewhere. You should be able to read continuity between all of the blades, with the highest resistance coming when you read through the contacts on the ends of the elements, and the lowest when you read from the contact for the power lead through the largest resistance element.

If the resistor checks good, you're going to have to pull out the switch and check it out. It's possible for the switch itself to go bad: I've seen it a couple of times on other vehicles. Other than that, you'll have to do some basic wiring troubleshooting.

Good luck!

 

On mine the fan switch just stopped working. I found the wire harness and the black wire was out. The plug was melted where the black wire was connected. Anyway I can't remove the plug from the resisitor because of the melted plastic. Tried to pry it out but don't want to break it but maybe I should because I probably need to buy the wire harness too. Any Ideas?

 

Wow!
I hadn't checked my post in a loooong time. I'm very happy it helped so many people. It's crazy how a scary problem has such a simple, low-cost solution.

 

Just buy a new resistor, or maybe go to a junkyard and find a good resistor and harness, They're cheap, and once you follow the ideas given here, it won't be a problem any more.

By the way, since fixing the problem in my old '99 F150, I have sold it and got a '03 Heritage Edition. The blower was working fine, but on a hunch I took a look at the connector at the resistor. Sure enough, the plastic showed signs of high temperature! I did the whole bit: i.e., cleaning, silicone grease, and etc., and put it all back together. After over a year, it doesn't look any worse than it did when I got it, and I expect it to last for a long time.

 

You saved me $200 plus. I used your info to fix my Jeep as well.

 

1998 XLT F150. This also was my problem. I had posted this in another F150 forum and did not even get a response. Thanks for the information.

 

BBB - is this fan motor resistor a simple fix in my '07 F150? Do I need to disconnect the battery before doing the job? Especially when you know the airbag is right above it - anyone? Thanks.

 

You dont have to disconnect the battery. Just disconnect the plug and take out the screws. Put the new one in and put the connector back on. It really is that simple.

 

Thank you bwquestion - I already did disconnected the battery (for a safe measure) before I got your answer. I replaced the resistor and now I have all fan speeds. It IS very simple.