New fan resistor installed...then MELTED...help?

o2G2o · Jul 1, 2011

I read this whole thread (and posted at the end of it) but I'm in a bit of a rush to find a solution so I thought I'd make a new thread (my apologies).

http://www.jeepkj.com/forum/showthread.php?t=26012

The Liberty belongs to my parents and they live a good 2 hours away. My sister's boyfriend (very handy guy, especially with electronics) swapped out the resistor and the fan worked normally again...for TWO MINUTES! After that the new resistor MELTED.

What on Earth could cause that? Incorrect fuse somewhere? Any help is appreciated!

TomO · Jul 1, 2011

I'm no expert on fan problems particular to the Liberty, but two things come to mind.

Possibly a shorted winding in the blower motor or a partially seized motor bushing? There is probably a resistance reading published somewhere on the 'net that will tell you what a good motor winding should read.

rocknrun · Jul 1, 2011

Are you sure he had the correct wattage on the resistor?

o2G2o · Jul 2, 2011

TomO said:
I'm no expert on fan problems particular to the Liberty, but two things come to mind.

Possibly a shorted winding in the blower motor or a partially seized motor bushing? There is probably a resistance reading published somewhere on the 'net that will tell you what a good motor winding should read.

That's over my head (and I'm sure over my dad's as well), but I think sis's boyfriend would understand that! Thank you, will investigate that.

rocknrun said:
Are you sure he had the correct wattage on the resistor?

As in, did the dealer furnish the right part?

A couple of other tidbits to consider (asked dad more about it):

1. the negative battery cable was NOT removed before installation.

2. the unit was left "disassembled" when testing/melting the new resistor. That is to say, it was plugged in, but not put back up into the dash and secured in place. I've heard these resistors run really hot, is there a resistor cooling system in place under the dash? If so it would explain why it ran so hot and melted...

Thanks for the help thus far!

rocknrun · Jul 2, 2011

o2G2o said:
That's over my head (and I'm sure over my dad's as well), but I think sis's boyfriend would understand that! Thank you, will investigate that.

As in, did the dealer furnish the right part?

A couple of other tidbits to consider (asked dad more about it):

1. the negative battery cable was NOT removed before installation.

2. the unit was left "disassembled" when testing/,elting the new resistor. That is to say, it was plugged in, but not put back up into the dash and secured in place. I've heard these resistors run really hot, is there a resistor cooling system in place under the dash? If so it would explain why it ran so hot and melted...

Thanks for the help thus far!

All resistors have 2 values; the amount of resistance (measured in ohms) and the amount of power the resistor can handle (watts). The more current, the more heat is dissipated by the resistor. The higher the current, the higher the wattage rating of the resistor should be.

o2G2o · Jul 2, 2011

rocknrun said:
All resistors have 2 values; the amount of resistance (measured in ohms) and the amount of power the resistor can handle (watts). The more current, the more heat is dissipated by the resistor. The higher the current, the higher the wattage rating of the resistor should be.

Ok that sounds somewhat familiar from my college days...

I might have mislead you with my last thing about the dealership...what I meant was, if the dealer gave us the correct part than the watts/ohms etc. must be correct, no?

Unless you're saying that we should be testing the power coming out from the truck's wiring before installing the resistor and make sure the values are not too much for the resistor? I assumed you meant there was something wrong with the resistor we bought but now I realize you could have meant the truck itself.

rocknrun · Jul 2, 2011

o2G2o said:
Ok that sounds somewhat familiar from my college days...

I might have mislead you with my last thing about the dealership...what I meant was, if the dealer gave us the correct part than the watts/ohms etc. must be correct, no?

Unless you're saying that we should be testing the power coming out from the truck's wiring before installing the resistor and make sure the values are not too much for the resistor? I assumed you meant there was something wrong with the resistor we bought but now I realize you could have meant the truck itself.

The dealership should have given you the correct part, but of course they could have made a mistake. I'm getting a little bit out of my element here since I haven't had any issues with my blower motor, but I would think if there was a problem such as a short or something it should have blown the fuse, not melted the resistor. How did the resistor look that was originally in the KJ? If it was melted too, then I'd assume you have a problem somewhere in the circuitry that's causing this. I would also inspect the contacts where the resistor plugs into and make sure they are clean and tight.

ridenby · Jul 2, 2011

Maybe bother in law is not as smart as he says. If you look there is an alternative that is more robust,or you could have a short somewhere.

New fan resistor installed...then MELTED...help?

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