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[HOW-TO][HVAC][Gen III Dakota][Gen I Durango] Blower Resistor Diagnosis/Replacement

273K views 139 replies 83 participants last post by  Hempshaw 
#1 · (Edited)
Since this question, or variations of it, comes up quite often I thought I’d write a thorough how-to which can be linked to or (hopefully) found in a search.


SYMPTOM:

Your heating & air conditioner blower motor suddenly stops working, only works on certain speeds, or just seems to not blow as hard as it used to.

Applies to (as far as I know):
2001 – 2007 Durango
2001 – 2004 Dakota


SOLUTION:

99.9% of the time your blower motor resistor block has gone bad. The resistor block is part of the ground path of the blower motor circuit, which in conjunction with the fan speed selector switch controls the speed of the fan by varying the amount of resistors in the electrical path (more resistors = slower speed, fewer resistors = higher speed). This is an easy fix and the new part costs less than $20. If you’re like me and would like to know for sure, read ahead to the “Troubleshooting” section. If you want to play the percentages and just go ahead and change it, skip ahead to the “Removal & Replacement” section.


TROUBLESHOOTING:

In order to troubleshoot the resistor block it will be easiest if it is removed from the truck (see Removal and Installation in post #2). Use the following diagram for this procedure.



Pin 2 at the top left goes to the motor, 1, 3, 4, & 5 go to the switch. What happens is a positive source is routed through a fuse and the ignition switch straight to the motor. The ground for the motor is routed through the fan speed selector switch and in turn the resistor block. When you rotate your switch, you are actually controlling the routing of the motor ground through this resistor block. Notice how if the ground goes through pin 5 then out pin 2 it has to pass through 3 resistors? That would be your low speed. See how there is a direct path between pins 1 and 2? That is your high speed. More resistors, lower speed.

If you look closely at the plug, you can read the pin numbers. Older styles may not have these numbers, so use the following picture:



With the connector tab at the top, pin 1 is on the left, pin 5 on the right.

It may also be on the vehicle side of the plug:



Measure from the following points (you should see approximately the following readings).

pin 2 to pin 1 = 0.2 ohms (very little resistance)
pin 2 to pin 3 = 0.7 ohms (some resistance)
pin 2 to pin 4 = 1.3 ohms (more resistance)
pin 2 to pin 5 = 2.4 ohms (most resistance)

If any of those combinations have no continuity, something is wrong with the resistor block. If all those resistance readings are correct, or you just love troubleshooting, you can do the following two steps by disconnecting the blower motor plug. (Here is what you’re looking for, follow the black and green wires around towards the front of the truck to find the motor plug)



1. Disconnect the blower motor plug (seen disconnected in the following picture, for this step you want the plug indicated by the blue arrow) and connect a wire between pin 2 and ground, then between pin 1 and a 12v source (fuse block, battery, etc…). This will verify the blower motor functions correctly. Notice in the picture the plug is held up by two friction tabs, you can pull down and release those tabs for easier access.



2. Using the following diagrams, and with the blower motor plug disconnected, connect one lead of your meter to pin 1 of the vehicle side of the plug (Red arrow), then the other meter lead to a suitable ground. Verify the resistor block is plugged in to the vehicle harness. Rotate the fan speed selector switch through all the positions and watch the resistance change on the meter (should be similar readings as above). This will verify your speed selector switch and all the wiring has proper continuity. If any resistance reading seems incorrect, and you have already separately checked the resistor block, continue to troubleshoot the speed selector switch and the electrical connectors themselves.






Continued in post #2
 
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#126 · (Edited)
Water in blower motor: I have an 04 Dodge Dakota. My second AC/Heater blower motor has died due to having water in it. The thermistor is fine. The water is clear not green, and I can't detect any leaks in the heater core. Any suggestions as to where the water might be coming from?

I will be forever grateful for whatever help can be given.

Thank you,
John
 
#127 · (Edited)
Last winter I replaced the resistor pack cause my 01 Dak blower had quit entirely. I put in the new resistor pack and all was good,....until last month. Now being winter again it is acting up. Similar, but not the same.

The blower works fine on speeds 3 and 4, nothing on 1 or 2. So I'm checking the resistor again. Couple of things though:
1. I still had the old resistor, and pin 2 is burned, which is the power input pin. When I put my VOM to it, all the readings are open for all pin combinations. That checks with the way it was not working on any speeds.
3. The resistor that just failed, looks burned on pin 3, but pin 2 is fine. So that explains why it works on two, but not all four speeds.
4. On occasion, I get a faint smell of antifreeze in the cab, just every now and then. But the water/glycol level in the system is good. Is it possible I have a pending leak issue in an area that drops water onto the resistor connector?

Where the resistor mounts, if there is a water/antifreeze source near it or right above it, it would have to drip directly onto it, if that is the problem causing the failure. Also, where the resistor mounts, it is raised up from the bottom of the duct, so water/glycol would have pool up to reach the resistor. I wonder if I have a pending heater core problem waiting to happen? Never seen any water/glycol in the cab on the floor, but I get the occasional hint of antifreeze smell in the cab.

So I got another replacement (OEM this time) resistor at the local dealer for less than $7, part number 0506 1575 AA-001. Installed it and all fan speeds are back to normal again. Perhaps the replacement I had before was a lesser quality aftermarket part. The OEM part has a translucent mount base like the original. But the aftermarket one had a solid grey base, without some fo the same details as the original one. We'll see how long this one lasts.
 
#130 ·
Yes, if you can... find a kit to do the blower, harness and resistor.

I burnt up another 2 resistors before breaking down and doing it right.

All parts easily accessible and it's an easy job. The resistor alone will give you a temp fix until it melts again.

I got a full kit on Amazon much cheaper than your local shop.
 
#133 ·
So I've had my Dakota for 1.5 years. I have replaced the resistor 3 times. The 3rd time, I replaced the plug and wires due to them burning up as well as the bower motor. That worked from Sep '16 until now (jul '17). Just today the blower stopped and started back again. Now, pin #2 burned up again on the resistor and on the plug. I'm not sure what else to replace since it's all been gone through. Any ideas on what my issue is? I went to Advanced Auto and spent another $12 on a BWD resistor instead of the cheaper Doorman brand. Maybe it'll last longer...maybe not.

What else could be causing my resistors/plug to burn up?





 
#134 ·
So I've had my Dakota for 1.5 years. I have replaced the resistor 3 times. The 3rd time, I replaced the plug and wires due to them burning up as well as the bower motor. That worked from Sep '16 until now (jul '17). Just today the blower stopped and started back again. Now, pin #2 burned up again on the resistor and on the plug. I'm not sure what else to replace since it's all been gone through. Any ideas on what my issue is? I went to Advanced Auto and spent another $12 on a BWD resistor instead of the cheaper Doorman brand. Maybe it'll last longer...maybe not.

What else could be causing my resistors/plug to burn up?
Have you replaced the blower motor yet?

Too much current through it will cause the resistor to run hotter.

RwP
 
#139 ·
I bought the motor brand new in last September through RockAuto. I'm not sure of the draw yet, I still have to check that. If I cant figure this out, I'll likely order the factory Chrystler fan, wire and resistor. I don't want to pay that much, but maybe then it'll work like it should. The fan itself is $133 from the Chrystler website, I paid $41 at RockAuto, maybe it's the name maybe it's the quality.

Fan P/N: 04885669AC ; 04885669AA; 04885669AD; 04885669AB
Resistor P/N: 05061575AA ; 04885635AC; 04885635AA; 04885635AB; 05061383AA; 05174618AA

ALl found here: http://www.factorychryslerparts.com...0300&ukey_driveLine=6803&ukey_trimLevel=18676
 
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