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Blower Fan Resistor

6K views 36 replies 23 participants last post by  lubichuk 
#1 ·
Hey folks - apparently this is common in Canada. The fan stopped working in all but the highest speed on my '03 Rubi. The dealer said "oh ya, we keep 'em in stock....." I got it, but I need to know where the resistor is.

Anyone done this before?

Thanks in advance
 
#2 ·
I just did it. It's right under the glove box. Look for a plug with 4 wires coming out. I took the glove box out. The resistor sits inside the duct.

It was kind of a PITA as I only had a simple socket set with a big socket wrench - use a little one. :)
 
#4 ·
Shamus said:
Thanks man - got 'er done.

Wish I had smaller hands or my daughter was better with the socket set!!
:laugh:
That's how ya learn! When I was little my dad/uncles always had me twisting little wrenches in tough spots. Once I had to pick a trunk lock from the inside.
 
#6 ·
you will need to remove the glove box (with a 1/4" nut driver to remove the strap) and look down and it will be behind the heater duct held on by two bolts. you will also need a 1/4" ratchet with 5/16" socket (for those two bolts). The service manual tells you to remove the entire dash but i was able to do it with just removing the glove box. becareful not to bend the new one. the location makes it uncomfortable to deal with but it was doable
 
#8 ·
kakirubi said:
Be prepaired. I have replace the one on my 03 3 times already. The last time I lost the two middle speeds. Gettin pretty good at replaceing them. :roll:
Change the blower motor. That's what causes the resistors to fail.
 
#10 ·
I just had this fixed on my 05. UNDER WARRENTY. :lildevil:
 
#11 ·
DoctorD said:
kakirubi said:
Be prepaired. I have replace the one on my 03 3 times already. The last time I lost the two middle speeds. Gettin pretty good at replaceing them. :roll:
Change the blower motor. That's what causes the resistors to fail.
What causes them to go bad? Is there a permanent sollution?
 
#12 ·
3rivers said:
DoctorD said:
kakirubi said:
Be prepaired. I have replace the one on my 03 3 times already. The last time I lost the two middle speeds. Gettin pretty good at replaceing them. :roll:
Change the blower motor. That's what causes the resistors to fail.
What causes them to go bad? Is there a permanent sollution?
The blower motor bushings get draggy, the motor will go up in current draw from the designed 10-11A to about 22A when it takes out the resistor. A new resistor will work for a while, but fail again, IF the blower motor still draws too much current.

This is true for almost the entire DCX product line.
 
#13 ·
DoctorD said:
3rivers said:
DoctorD said:
kakirubi said:
Be prepaired. I have replace the one on my 03 3 times already. The last time I lost the two middle speeds. Gettin pretty good at replaceing them. :roll:
Change the blower motor. That's what causes the resistors to fail.
What causes them to go bad? Is there a permanent sollution?
The blower motor bushings get draggy, the motor will go up in current draw from the designed 10-11A to about 22A when it takes out the resistor. A new resistor will work for a while, but fail again, IF the blower motor still draws too much current.

This is true for almost the entire DCX product line.
That last line about the entire DCX is sure true. My friend had his go out on his 06 Power Wagon with only 10,000 miles.
 
#14 ·
So, the solution is to buy 3 power resistors two to three times the wattage of the stock resistor bank? (the highest position bypasses the resistors)
 
#16 ·
kakirubi said:
How hard and expensive is it to replace the blower motor?
I was wondering that too, but the new one will just start eating resistors after 30k miles, right?
Unless there's an aftermarket motor to be had.
 
#17 ·
Just replaced mine. :D
Looking forward to the Tech. article, "Blower Resistor Upgrade" also included in this article , " How to double your CFM." or " Turbo Blower" get the sensation of traveling 70mph while stuck in traffic.
 
#18 ·
3rivers said:
So, the solution is to buy 3 power resistors two to three times the wattage of the stock resistor bank? (the highest position bypasses the resistors)
No, there's still a thermal fuse in the stock setup. Defeat that and you'll light the ducts on fire.

The blower motor is an easy replacement and not terribly expensive.
 
#19 ·
DoctorD said:
The blower motor bushings get draggy, the motor will go up in current draw from the designed 10-11A to about 22A when it takes out the resistor. A new resistor will work for a while, but fail again, IF the blower motor still draws too much current.

This is true for almost the entire DCX product line.
That explains melting switches and wires pretty well too. Can the fuse be lowered so that it blows before the wires, switches and resistors get taken out?
 
#20 ·
ekim said:
DoctorD said:
The blower motor bushings get draggy, the motor will go up in current draw from the designed 10-11A to about 22A when it takes out the resistor. A new resistor will work for a while, but fail again, IF the blower motor still draws too much current.

This is true for almost the entire DCX product line.
That explains melting switches and wires pretty well too. Can the fuse be lowered so that it blows before the wires, switches and resistors get taken out?
Not really. The switches usually melt because the pins are crap. I use dieletric grease to act as a heat sink and that usually cures that problem.

The real issue here is to prevent the overload. A lower fuse will trip on startup, since a stopped blower will draw a good 30A on initial startup, then it'll drop dramatically as it comes up to speed (counter EMF).
 
#21 ·
Yea, in industrial applications a slow blow or motor starting fuse would be used. Not really worth the trouble or engineering here. Espically since the failure mode leaves you with a HI blower. A smaller rated, but motor capable fuse, would leave you with no defrost or heat while saving the resistor.

A resistor with a thermal/overcurrent failure is easy to spot. It just needs to be pulled for service shortly after you notice the failure so the thing doesn't corrode. A nasty corroded one likely failed from nasty corrosion. One with an open thermal device, or one that looks like it got hot failed from ... heat (current).

If you are really offended by the whole series of events you can just run it in HI until it pukes. Experience tells me you could get years if you are lucky. The fuse in the circuit will save you from wiring disasters. On old Fords I used to drill the rear bearing bulge on the back of the motor. After a few drops of oil the thing would work for months.
 
#25 ·
Man this is weird,happened both my fathers jeeps this week,i just ordered the parts for him from advanced,hasnt happened to mine yet knock on wood.
 
#26 ·
JP had an article a few months back that summarized a writeup I recall seeing on JU - basically wiring 3 relays up to replace the resistors. However they still got H-O-T and they said this month (in response to a letter to the editor) that they ended up replacing the blower motor too. They did comment that the relays should be able to handle the higher heat and not cause a problem, but that's a lot of heat to trap back in the dash with a lot of wires around it...

The problem with repeatedly replacing the resistors is eventually the plastic plugs will melt...so do the fan at the same time as the resistor!

Interesting aside - the resistor just went out on my 85 BMW daily beater, however they don't recommend replacing the blower fan because it's the contact on the resistor that fails, not the fan motor pulling amps. Replacing it was a breeze, it's mounted on the fan motor which is accessed through a panel on the firewall from the engine bay, and the really slick part of the design is it's cooled by the fan airflow (before the heating coil), maybe that's why it lasted 23 years and 200k miles! Oh, and it was $30 to replace....might be the only BM-TroubleU part that's cheaper than a Jeep part, haha!
 
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