Heater Blower Fan Fix - Only High Speed

BlueBobbyBird · #1 05-29-2009, 10:08 PM

I did my search and found plenty of help.
I would like to thank everyone who contributes information. It sure helps.
I thought I'd contribute a couple pictures.

My truck ia a 1999 F150 with manual heat/ac (115,000? miles).
My fan was working on high only. With the clues from this forum, I went straight for the resistor. And look what I found...

From the amount of rust, I've apparently been missing a couple speeds for a long time. The melted plug could have been more recent and took out #3.

For a recap:
The resistor is located on the passenger side, under the dash, near the firewall. It's difficult to see.
If you look near the kick panel, you can see the wire harness and the plugs. Follow the wire to the resistor.
The two resistor screws are pointed straight up and mine took an 8mm socket. I removed mine by feel. (unplug it after you remove it, so you can see it better.)

Zeevert

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BlueBobbyBird · #2 05-30-2009, 03:10 PM

I picked up the new resistor today at the local Ford dealer.
p/n 4L3Z-19A706-AA
$28.14 plus tax
in stock

They didn't have the wire harness in stock, but it was going to cost over $38.

I "repaired" the old plug and put it back together. Fan works great.

Zeevert

BlueBobbyBird · #3 06-01-2009, 01:14 AM

One last picture under the Glove box...

Zeevert

87fiveoh254 · #4 06-02-2009, 09:40 PM

Wow! I can't believe it rusted/melted like that. Nice article!

bjp207 · #5 06-02-2009, 11:10 PM

I just did this on my dads 01 f-250, it was slightly different, but the same concept. Good write up!

ferchja · #6 06-05-2009, 12:18 AM

Just found this article was having the same issues. Mine also melted at the connector. I am logging this with NHTSA. This seems to be an obvious fire hazzard.

Jeremy

cootersfx4 · #7 06-05-2009, 09:36 AM

I just replaced the Resistor Pack (Board) on my 2002. Much the same scenario, but my connector was perfect. And an interesting thing was the amount of corrosion in comparison to the resistor packs on my 1986 and 1985 T-Birds (pulled near the same day). The T-Bird packs were corrosion free. Ths most likely has something to do with the Pack being on the bottom of the case in our trucks.

Cooter

Auburn1997 · #8 06-14-2009, 04:20 PM

I have the same problem with my 1997 F150. I didn't notice the harness trouble until after I had purchased the new resistor. I purchased the resistor based simply on the symptoms, before inspecting it. I would like more information on repairing the harness, which I would like to do without investing another $38. Are the plastic adapter ends pretty standard? If so, do I find them at an auto parts store or somewhere else? And are the wires soldered into it? Thanks.

fc143 · #9 10-31-2009, 01:32 PM

My lower two blower speeds were not working and my AM radio was getting alot os static. Changing this resistor did the trick, now everthing works again. Thanks, Steve