MDeal5

I've seen some posts that relate to earlier models, mostly with the manual control switch, but I haven't seen one that seems to relate to my problem. I had to replace the heater core recently and the blower motor had stopped working about a month before I had to replace the core. The connector under the dash had melted and fused with the resistor and I couldn't remove either of them without destroying both, so I replaced the resistor and the connector. When I checked the fuses, the 40A fuse under the hood is blown and immediately blows when I replace it if I plug the wiring harness into the resistor. And I believe it would be easier to uncover national security secrets than to find wiring diagrams and assistance for models with the AZC, which I unfortunately have. I've replaced the control switch in the dash and this didn't help the problem at all. Can anybody give me some help here? I hate to trash the vehicle because of a wiring problem, but I'm to the point where I'm about to just run new wires from the battery to the blower motor and put a manual control on the blower motor. Any and all assistance would be greatly appreciated.

One final note, there are 3 wires. A red and a black 12 gauge wire and a blue 16 gauge wire. The red wire is hot at all times if the 40A fuse is in play. Even with the ignition switch in the off position. The red wire is the one that shorts out the system whenever I try to plug it in to the resistor or reconnect it to the wiring harness. Also, I have the red wire on the J1, the blue wire on J2, and the black wire connected to J3. This matches the only picture that I've been able to find of the 3 wire arrangement going in to the blower motor resistor.

Thanks in advance for any assistance you want to offer.

NVJeep

I have had the same problem. The hot wire melted the connector and part of the resistor block. Last time I just replaced the wires and connector in the immediate vicinity of the controller/resistor with dealer thicker wires and connector and have not had a problem (except the controller casing is still partially melted)
However, I did come across another fix. I think it is Dorman and Airtex that make an adapter for a newer style of controller. It is slightly smaller, but more reliable, and much cheaper - $55 or so vice $200 for the old style one. I think you may have to change out the connector also but that is all included in the kit. Last I looked they didn't even show the original. I suppose everyone but Jeep has realized that it is a fire hazard.
It is a fairly easy install. Hardest part is splicing in the new wire since you have to crawl up under the passenger dash and work with short wires in a tiny space.
Also check that the red wire has not chaffed on the fan casing as that is a tight spot where it wraps around to get down to the controller.

NVJeep

Also check that the red wire has not chaffed on the fan casing as that is a tight spot where it wraps around to get down to the controller.
please Delete, info added above

MDeal5

First, thank you for your response. I have been unable to locate anything but the old style controller and the new ones run around $500 everywhere that I've seen them. Do you have a model number? or something you can share that will help narrow the search?

Second, I replaced the connector and as much of the wiring as I could reach with the replacement 14 gauge wiring. Nice of 'em to make all 3 wires green. Really helps when you're trying to make sense out of scorched black insulation in a dark cramped space, but I digress.

So. Is the hot wire supposed to stay hot even with the ignition off? I'm wondering if I've got a burnt fusable link or relay that I can't locate.

Does anybody have a wiring diagram that could help me unravel this gordian knot, or at least help me figure out how far I have to trace these wires to replace them?

Thank you again. I"m getting tired of driving around with my console in the back seat and a huge hole in my dash!

NVJeep

I found the kits on Rockauto. I have used them for many parts and have always been satisfied. I didn't ask what model you have, but I don't think it matters much if you have ATC (You set the temps with a numeric temp input). You will have to go to the site and drill down for your vehicle anyway. Here is the link for the Dorman Kit:
http://www.rockauto.com/catalog/more...640&cc=1381452

The Airtex one is there too. They are both $76 or so and come with the all the parts and INSTRUCTIONS. I don't have any wiring diagrams. The OEM controller is a 4x5x2 rectangle with little stubbies on the top. The new one has spikes the look like they are about 2" or so. The new one is also smaller and has a different connector but the kit has everything you need.

WHILE YOU HAVE THE DASH OFF:
You may want to verify that all your recirc and blend doors are working. They are notorious for failing. The problem is that the actuators are very strong and break off the stop pins. The motors then break the doors where they attach to their respective shafts. The Recirc door is on the top right as you look at the dash. The other two (blend doors) are inside the plenum to the left of where the glove box would be and blend air for their respective side. The drivers side is the one you can see and the pax one is behind the plenum (toward the front of the car) If you feel cold air on the pax side in the winter, the recirc door is probably broken. You have to pull the dash at least partly to change it out. The blend doors can be replaced with the dash in place, but you lose the independent control -long story. If you change the blend door with the dash out, you can install a kit that maintains the independent controls.

So you may ask why you dont just replace the whole plenum? Well, you would just have the same problem in 3-5 years again and would be out $350-500. The aftermarket kits are about $80 for both the blend and Recirc doors and are metal shafts and pins. The one I installed was made by Dorman, but Airtex or Standard Parts may make them too. The Dorman folks were very helpful, especially after I pointed out to them that they had their literature backwards (the manual temp and the auto temp doors). They have fixed that problem and it looks like they have the right part descriptions now.

Hope you get it fixed.

MDeal5

When I took the dash out to replace the heater core, I went ahead and rebuilt the entire plenum. New actuators and the whole nine yards. Didn't want to have to pull that @#$@% dash out again. I had all the fun I wanted to have with that the first time around.

So what I'm hearing is the dash has to come out again in order to trace the wiring and find the fault. Ugh. Not the best news I've had, but I do sincerely appreciate all of your help with this! Hopefully this will get me far enough out of the ditch that I can defrost my windshield again someday soon!

Thanks!

dave1123

After you got it all back together, did you have any screws left over? I did the same thing with a Dodge and when I was thru, I had 2 sheet metal screws left. IDK where they went, but I had a squeak in the dash until I got rid of the car.

Cherokee_Mike

I recently had to replace the heater resistor in my 2000 WJ - for the 3rd time in 3 years due to the unit & connector melting - poor design, I don't think the connections are good enough to handle the current. I used the kit detailed above from Rockauto although mine came from a supplier here in the UK. I had to reverse the connections at one end of the motor cable as the fan ran backwards !
I also had to replace the blend doors and did this with the dash in place through the glovebox.
It is possible to retain the independent control - I didn't cut the centre plastic part between the blend doors through completely through but used a small battery operated 4.5v soldering iron with a fine tip to create a 'score line' where it would normally be cut - just enough to fold it back and change the blend door - then I just folded it down into the normal position and it 'clicked' into place.
Using the soldering iron to cut into the heater box saves an awful lot of mess which you would get using a saw or Dremel type power tool. Took a while but then no mess to clean up.