Replacing blower fan resistors

[James Morse]

Two 8mm bolts - kind of hard to get to, but should be able to do it. If I could take the wiring harness off it would help a little. It looks like there are plastic clips holding it on there, am I right about that? Trying to not break anything. I can see the 8mm bolts, it's just a matter of maneuvering the right length socket wrench into there. Probably I'm making it harder than it is. Anyone has done this?

 

[ericbphoto]

Patience. Should be able to unplug it. The clips get brittle with age. So don't pry them too much.

 

[RobbieD]

To me, the wiring connector is easier to remove before unmounting the resistor block, others have better luck with it unmounted.

GENTLY use a tiny screwdriver, seal pick or other tool to pry the locking tab up JUST enough for it to unlock and slide up the catch. A little WD-40 can help if the connector's stuck. Go slow and be very careful, as the old connectors break easy.

Before you plug the connector back into the new block, clean the terminals good (spray contact cleaner works great), and I'm a great believer in using dielectric grease to help seal the reconnected contacts from oxidation. The fan can pull some current, so pay attention to any burnt-looking or corroded connections.

 

[James Morse]

You are using the dilectric grease just on where the parts seal, right? Or are you putting it on the actual terminals?

On my way to Harbor Freight and Northern Tool, between them looks like I can get the CRC QD elec cleaner and the dilectric grease.

 

[ericbphoto]

You are using the dilectric grease just on where the parts seal, right? Or are you putting it on the actual terminals?

That is correct. Just sealing surfaces.

 

[James Morse]

Turned out to be a little more than I bargained for. Got the old resistors out, but, 3 of the 4 terminal connections did not come with it, they are corroded solid into their mates. Plus the old connector is partly melted, and that should have been a clue to me to just cut it off. I was real careful taking it off but I'm afraid the thing is just fubar. I'm headed to Advance now for the connector. Looks the same in the picture. Since it's already pigtail wired, it'd just be a matter of getting the wires to the correct wires and splice them in. Then test the new setup works before re-installing.
https://shop.advanceautoparts.com/p/carquest-premium-hvac-blower-motor-resistor-connector-pta1009/12446717-p?product_channel=local&store=6066&adtype=pla&product_channel=local&store_code=6066&gclid=EAIaIQobChMI_PizmdeQ8wIVBIizCh1pagJcEAQYAyABEgK6CPD_BwE&gclsrc=aw.ds

 

[fastpakr]

Definitely looks like the right connector. If you're able to get in there with a soldering iron, that's the best option. Use heat shrink too (marine grade if it's available).

 

[James Morse]

Yeah I soldered it up and I used the thicker marine heat shrink from Harbor Freight. All working great now for the different blower fan speeds!

It was a lot more work than I'd anticipated. Nice to have it working though!! If I have to do it again it won't take me so long. Should last a while though.

THANKS!!

 

[RobbieD]

Thanks for letting us know how it turned out. Congratulations; you did good on the repair.

 

[James Morse]

Yeah, thanks, it's been a while since I soldered.

When putting the new one in I was afraid to reef much on the little 8mm bolts, they are going into plastic, I think, plus the resistor mounting isn't very strong, so I just went enough so they felt snug and the unit didn't wiggle at all in its mounting.

I think a small (1/4" drive) ratchet drive would be maybe good for this. Here's the lengths that worked for me for a 3/8" drive, a 1/4" drive might work better in terms of being able to turn it more 'clicks', it takes a long time to get them in/out. That is really the hardest part of the whole thing is finding the right tool to fit in there straight onto the bolts.

If I ever had an old one like this I think because I couldn't get the connector off until I got the thing out, it probably would be about as efficient to just cut the wires to the connector, that makes it somewhat easier to get to the bolts (although you don't have to have the connector off to get it out). Have the new connector and resistors ready, and just do it.

Strip the existing wires with a razor blade, go in a circle around, then slit lengthwise, and peel it off. Because it probably won't just slide off using your strippers. If it's black/dirty, fine sandpaper to clean up. Tin well all the ends first with solder this makes it much easier to join them. Use a little alligator clip or like to clip the existing wire to something close to hold it still. Then you will have enough hands.

The marine shrink wrap is at Harbor Freight, it's slightly more money than regular but it's peanuts, and it's thicker than the normal stuff.

When I wrap things all back up I slit big pieces of the shrink wrap and put around the wires, not shrunk, before I tape them, because that black electrical tape sometimes gets all gummy on the wires, so that way you can take it apart if you ever had to later on and not have a big mess. Theoretically you could put these big pieces of wrap around the wires before doing the re-connect, but I was so worried about mixing up the connections I did them one at a time, so then you can't slide the pieces on afterwards (yeah - remember to put your shrink wrap on, that you shrink around the solder joints, before you hook them up!).

Here's the wires soldered and shrink wrapped, but before fully wrapped:

Then I wrap them all the way up to the connector, as described earlier. Don't forget to test it before putting it all back together. The new parts you will be able to get the connector on and off rather easily, unlike the old one. Leaving the connector off while re-installing the resistors makes it somewhat easier to get to the bolts.

I sure appreciate all the help.

 

[professor229]

I thought I would post today about getting this done yesterday.... I ordered the part about a month ago and had some free time yesterday so I had at it.... I watched a few You Tube How To videos and it seemed pretty straight forward and like everyone else commenting I thought it should be pretty easy.... The plan? Remove the air intake box... and when I replaced the fender I was smart enough to spray the rubber mounts with WD 40 so they should pull out easily.... Then I would remove the combo coolant overflow/windshield washer fluid reservoirs..... no cruise control so after that I should have a straight shot at the two 8 mm bolts.... simple... right? The air intake box argued a bit but one last big pull got the two rubber mounts to release on the bottom... I was impressed with the design of it though... Next, the four connecting points on the reservoir... the two screws came out right now... the one nut fastener to the inner fender well? missing and a broken plastic part on the reservoir... the inner nut? rusted so badly to the fastening screw that there was zero chance...... It had to be cut off... which took some time... tough to get a die grinder in this location and I didn't want to accidentally cut the reservoir..... that took some time. No argument from the two 8 mm screws and I pulled the entire unit out far enough to work on it after removing the negative post from the battery... I drew a quick diagram of the wiring harness and four colors etc... and snipped the wires far enough back to leave be able to refer back to the original. The one thing I didn't do is note how the assembly came out from the firewall.. and later I would find out that it can only go back in one way for the screw holes to line up... Long story short... I rewired it... slapped it all back together and used two self drilling screws to reattach the reservoir to the inner fender well... and found out that that air intake box goes in a lot better disassembled and with a little more effort than the video showed... in other words... push harder.... Then I had some fun... negative post back on and I should have tested this all BEFORE I put all the extras back together but it didn't happen..... turned on the ignition and I have all the speeds now but there isn't a great deal of difference in the speeds that I can tell... but they all work. Then I went over to the bench and tried to remove the plug in to the resistor and forget the tabs.... I just broke them off to make it easier... so what was holding the plug in? Grabbed a plumber's slip wrench and tried to grab it enough to pull it apart.... nope.... put it in a vise and tried a hammer and large screwdriver to force the plug out.... nope.... got a bigger hammer..... nope... and by now, the entire old resistor assembly was getting to look pretty sad.... I never got it apart and we all know why......

 

[James Morse]

Sorry you had all this trouble. Not sure why you took out reservoirs, they aren't in the way, at least on mine, so your setup must be different. Speeds should be distinctly different at each setting, maybe check wiring or check that resistors are correct part. Hope it works out eventually, let us know. Can't think of anything else unless selector switch is somehow fubar, which you could check to make sure it's only sending voltage to -one- of the wires at each setting. Or if fan was fubar then it wouldn't go to the high speed, maybe, but usually when they are fubar they make noise. In my experience. Other guys know more than me for sure.

 

[sgtsandman]

After I found that the one in my 1998 darn near caught fire, I RTV's the crap out of the back side of the replacement and the replacement pigtail so water wouldn't get in there and do it again. I did the same thing soon after I bought my 2011 since it has the same setup. I do keep forgetting to check the 2019. Having the resistor in the engine bay seems to be a common theme with Fords.

 

[professor229]

I think I could have tried to get the resistor out without taking out the air intake and the double reservoir... and in the video there was a cruise control unit the guy took out too.... The only reason for removing it all was to get a straight shot at the two 8 mm screws.... Like I said, there was ZERO chance at getting the plug out of the resistor assembly.... so out came the entire thing. drew a diagram of the wiring to make sure it was put back right....

I will attach a picture of the old resistor... and laugh if you want to.. but I tried to get the plug out using a vise and hammer and slip pliers... literally everything and it still will not budge....

When I tested the switch before I started this, it worked only on the highest setting.... but at least it worked... Now there is a difference in the speeds and all the speeds do work... I can live with it the way it is now... I wish I had taken some more time in finishing it to prevent future rust out but the way I figure it, this unit worked for 18 years.... and 18 years from now I am sure I won't be using this truck!!!

Anyway.. the how to video kind of hints you can do all this in about a half hour.... It took me three hours because of rusted components..... but it was worth it.. This is the last mechanical fix on the truck... and maybe I will need to have it aligned... This morning I spent five hours doing body work on it.... It was a good morning ......Take care.....

 

[James Morse]

Cool. Yeah you definitely want to take off the air tube, other stuff just depends if you can get to the fasteners. That's why I bought a really short handle socket wrench. Like I said yours might not be totally same as mine. Old resistors are of course trash and the pigtail too, on mine when I took it off the contacts were fubar so I went and got the pigtail. Common problem with old trucks is lots of times stuff is just stuck. Knowing what I do now, if I did it again, I'd just get the resistors and pigtail at the same time and assume I would be trashing them and soldering the wires back. Wow if that's the last fix you are doing great. I have dash bulbs and cruise buttons to replace, have the parts, just haven't done it yet. Glad it's working for you now, nothing like having heat in the winter and having fan always on high isn't great.