Dropping resistor

[daveran2008]

Thanks for the advice. Yes $185, and the revised price of $92 sounds quite excessive, but it is Ford after all. I think that I'll Scoure the wreckers first. If they fail by having the wire corrode off the ceramic body then that is a visible way of seeing the good ones from the bad.
Daveran

[12Ounce]

Daveran,... assuming you are working on a '99 or similar:

You may want to take off the front "bumper" and have a look. Not a big job. The resistor pack is under there somewhere (I saw it ... but I don't even remember which side) .. and you could a photo to send to whomever you are ordering the part from. ... and I suspect the resistor pack is repairable, it doesn't look that high-tech ... you may not need to order anything.

[searcherrr]

Originally Posted by 12Ounce

Daveran,... assuming you are working on a '99 or similar:

You may want to take off the front "bumper" and have a look. Not a big job. The resistor pack is under there somewhere (I saw it ... but I don't even remember which side) .. and you could a photo to send to whomever you are ordering the part from. ... and I suspect the resistor pack is repairable, it doesn't look that high-tech ... you may not need to order anything.

Daz even betta. lol

Also a thought - if corrosion is what causes these things to just "fall off" rather than just the resistor going bad perhaps surrounding it with RTV, liquid rubber (paint on with a brush), or that new spray on rubber I've seen (both at wal-mart auto) would be a good idea.

[searcherrr]

I don't know about you guys, but I get the vibe that this is one of those parts that is gonna go obselete sooner rather than later. I did a lil research on what a dropping resistor is exactly. I'm assuming that the fan's really only have 1 speed (high or full speed rather) and that this dropping resistor is a way to reduce electricity to the fans to create a low fan speed since a "dropping resistor" resists voltage only to a certain point.

This makes me think... how come a normal resistor like the kind you see on electronic boards couldn't be used in place of this weird clunky ceramic thing? What someone would need to do is test the resistance of a new one to figure out what other resistor we could use (in theory) unless the ceramic thingy also has something to do with heat which I doubt since it sits in a plastic seat.

Well, as I've been trying to fix this "almost stall problem" on my van it ALWAYS 100% of the time almost stalls as SOON as the low-speed fans turn OFF. Reading up on Wiswind's dropping resistor info finally made me go look whereas I'd been resisting (huh huh) to look at it in the past cause it was just too damn easy. Sure enough tonight I saw that the leads are all rusted/corroded and the dropping resistor (which looks like a narrow ceramic horseshow) and that it was also cracked in various places and pieces of it are off at the leads. As I was trying to think of it like an electrical engineer might... since the resistor is made of ceramic the more pieces of it that fall off the less resistance there is for the leads to run through. Perhaps when my fans are cutting OFF this less resistance amounts to an electrical surge or short or even a loss of voltage somewhere. Trouble is I don't know which, but I do know this thing is broke and has to do with fan speed operation.

I have verified that the part number XF2Z14A601AB daveran2008 shared is correct. I did an exhaustive search and here is where I found it the cheapest though I wouldn't doubt if you call 20 Ford places you could probably find it cheaper somewhere up North: http://www.forddirectonline.com/part...?siteid=214462 - Ford Direct Online selling it for $53.70 - I ordered mine tonight.

Not to replace, but to supplement the wonderful Windstar parts photo library Wiswind has put up for everyone here are some photos of my broken dropping resistor:

[daveran2008]

I thank you for the great pictures and information.
Daveran

[12Ounce]

Those are good pictures. But I'm pretty sure your resistor does not look like the ones on my '99. (I will take a photo of mine when I install a larger tranny cooler ... in the not too distant future, I hope.)

Electrically the different model year resistors all have the same, simple task (You described it pretty well) ...They provide a reduced voltage to the fan motor for reduced speeds. This means they absorb electrical energy and must dissipate heat energy ... thus the locations "mounted in air".

Any suitable resistors obtained from Radio Shack, or the like, should work just as well. The resistors must be of proper value ... or Ohms ... to provide the intended speed reduction. Does anyone happen to know what this is??

They must also be able to dissipate the heat ... thus the resistors must be of a certain "wattage" value also. (Typical resistors on a radio or tv printed circuit board are 1/4 watt.) My '99's fans are protected by a 50 amp fuse ... therefore the total wattage supplied to the fan(s) and resistor pack is ... 50 amp X 12 volts ... 600 watts. The original resistors are probably rated at 250 or 300 watts. If you could find resistors rated at 500 watts, or higher, that would be even better. Higher wattage resistors will only mean they can handle the heat better ... probably be a little larger ... and probably cost a bit more.

Now all we need is the Ohm value(s). ???

EDIT; Corrected my math a bit.

[searcherrr]

Originally Posted by 12Ounce

Those are good pictures. But I'm pretty sure your resistor does not look like the ones on my '99. (I will take a photo of mine when I install a larger tranny cooler ... in the not too distant future, I hope.)

Electrically the different model year resistors all have the same, simple task (You described it pretty well) ...They provide a reduced voltage to the fan motor for reduced speeds. This means they absorb electrical energy and must dissipate heat energy ... thus the locations "mounted in air".

Any suitable resistors obtained from Radio Shack, or the like, should work just as well. The resistors must be of proper value ... or Ohms ... to provide the intended speed reduction. Does anyone happen to know what this is??

They must also be able to dissipate the heat ... thus the resistors must be of a certain "wattage" value also. (Typical resistors on a radio or tv printed circuit board are 1/4 watt.) My '99's fans are protected by a 50 amp fuse ... therefore the total wattage supplied to the fan(s) and resistor pack is ... 50 amp X 12 volts ... 60 watts. The original resistors are probably rated at 25 or 30 watts. If you could find resistors rated at 50 watts, or higher, that would be even better. Higher wattage resistors will only mean they can handle the heat better ... probably be a little larger ... and probably cost a bit more.

Now all we need is the Ohm value(s). ???

I'm going to measure the Ohm resistance of the BRAND NEW one I have coming and post it back. The order gets processed tomorrow when they open. The only thing that bothers me about the resistors at radioshack now that you mention the need to dissipate heat energy is I wonder if those ones do "dissipate heat energy". IE: More surface area = dissipate more heat energy.... and the ones at radioshack or that I was thinking of on electronics boards are smaller and with not much surface area at all. Still though it seems pretty ridiculous to me that this clunky thing exists on our vans. I'd be curious to see what is used on the 99's and up cause I may switch to it if the same fan motors/specs are used and if the 99's one isn't made of ceramic.

I was thinking about my idea of putting RTV all over the new one. I don't see why that wouldn't work to help keep it preserved over time. I'm sure the main element is electricity that degrades it over time, but its also exposed to outside temp/humidity daily which contributes to cracking it over time I'm sure. RTV isn't conductive so I wouldn't think that it would create more resistance.... but if its wearing a coat of RTV it would most definitly interfere with heat dissipation. Bummer. wa waaa lol

EDIT: Just saw your explanation of watts and more heat. Well since thats the case then GOOD. lol - If I can obtain the ohms from the brand new one this may give everyone a workaround or just let us know if we can use the 99 and up resistor.

[12Ounce]

Yes, the ohms values will be very important to others.

I didn't mean to imply that the resistors were THAT different on the '99. They are still ceramic ... but just simple straight square corner cubes ... not the rounded edged casting as in your photo.

I have seen such high wattage resistors on some very old electrical equipment. Don't expect to find such on the shelf at Radio Shack ... but probably something they could order.

[12Ounce]

I believe mine were similar to the wire-ended ones here:
.
http://www.heiresistors.com/ceramic.htm

[daveran2008]

I received a reply from Haynes regarding their lack of information on the Radiator Fan Dropping Resistor in their manual. They sent me two diagrams, one of the engine compartment, and one wiring diagram. The engine compartment diagram for the 99 Windstar shows the socket for the resistor is in front of the battery on the drivers side. Hope this helps others with same question.
Daveran

[searcherrr]

Hopefully the part will arrive this week. I'm trying to get them to give me the new tracking # for reshipment as they botched the first order completely.

[searcherrr]

I have the new resistor. I'll be posting a pic of it soon. I measured resistance of 0.0 ohm and other times consistently 0.3 ohm. I wasn't using the "Cont" setting which makes a continuous beep sound when testing the ohms. Don't think that makes a difference though beyond just the "beep".

EDIT: I tested with switching the probes using the regular ohm setting and I'm still able to get 0.00 ohm often and very rarely 0.3ohm. Then I switched it to Cont for the beep and ohm testing and sometimes it starts at 1.1 or .9 or .7 and works its way down "ALWAYS" to 0.3 ohm. Some of the time (like 1 out of 10 or 1 of 8) of tests I did with Cont resulted in 0.0ohm. Am I just seeing the "dropping resistance" possibly here? Anyone make sense of any of that?

The people of Ford Direct Online must be illiterate or simply not paying attention at all. This is the 2nd time in a row they have sent me the wrong part (regarding the radiator cap). Instead they sent me a WHEEL ORNAMENT!!!!! At least this time they sent me the correct resistor. So for this order we're 1 of 2 correct and overall both orders were botched. I have to send this damn thing back again now. I think I'm gonna just have them credit me for the rad cap because this is ridiculous.

EDIT2: Also note that there seems to be a "Resistor Asy" (assembly of course) part number as we said: XF2Z14A601AB and on the new porcelain resistor itself is a different number which may imply to me you can order the porcelain dealy by itself. The number on the porcelain resistor wouldn't probably be seen on broken ones cause of fallen off pieces: XF2H-8L603-AC and above that is a number IRC 0027 which I have no idea what that is. I just searched for XF2H-8L603-AC in Ford Direct Online's parts web site and it doesn't come up. So I guess we might have to order the assembly which bites because this new assembly looks useless for my year Windstar anyway.... although it does seem like this one would help dissipate heat better if I can mount it the way it came.

EDIT3: There is a 30A fuse (hope thats a fuse; dunno what else it would be marked 30A) molded into the wire leading to the left most plug/port on the connector (ie: if you are facing the connector plugs with the blue part at the bottom).

[searcherrr]

Ya'll think I should figure a way to put it in with the new bracket or just take it out of the new bracket? I looked and on my 95 the little tray that holds it elevates it slightly as well, but this new bracket of course elevates it a bit higher (heat dissipation).

[tomj76]

I apologize for reviving an old thread, but I'd like to know if anyone identified the requirements for the resistor. When I was doing some recent work on my Windstar, I noticed that the resistor had failed (for the second time). Thinking along the same lines as searcherr & 12Ounce, I want to see if I could find the resistance and power handling of the Ford device and substitute a more permanant solution to the problem.

The big issue is the current handling (and therefor power dissipation) of the resistor. My initial guess is something around 200 watts power handling. The resistance is small < 0.1 ohms, but the current is large, so it needs to handle a large amount of power. The heat of the engine bay on a hot day has to be accounted for as well. You can get catalog resistors that will handle 50 watts, and a combination of several could be made to get to 200 watts power handling.

Does anyone know what ratings are required for the dropping resistor?

[tomj76]

Apparently, Ford no longer sells replacements for this part. I called a few salvage yards, but no luck there. I did some testing on the resistor that failed, and determined the resistance to be 0.15 ohms.

FYI, you can't measure this resistance value with a standard DMM, because the contact resistance from the leads will swamp the resistance reading, and because the resolution of these meters is usually on 0.1 ohms. The only way to measure this value of resistance is to use a Kelvin resistance measurement.

The circuit this resistor is found in is fused by a 40 Amp fuse. Therefore, the maximum power dissipated in the resistor is Pdissipated = 40 * 40 * 0.15 = 240 watts.

I did some searching on-line, but could not find anything matching (or exceeding) this power rating. Ohmite makes a 0.1 ohm, 50 watts resistor, and six can be combined to make a 0.15 ohm equivalent resistor capabale of handling 300 watts.

The remaining problem to be solved is adequate cooling of the resistor (FYI, 300 watts a little less than 1/2 hp, so there is significant heat involved here) If the resistor is not kept cool, then the power handling will be reduced from the specification.