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Old 06-10-2010, 09:48 PM   #1
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Writeup for JP Blower/Heater switch fix

I am sure a lot of you have seen or heard of this article from JP magazine about fixing an overheated blower/heater switch with relays:

Jeep Fire Prevention - Jp Magazine

Some of you smart ones were able to fill in the blanks left by the article, the rest of us were left scratching our heads. For those of you like me, here you go...

According to the article (Although many folks in this forum debate against the article's assertion that this is the cause for melted switches), older blower motors draw more current than the switch was originally designed for. The larger current draw heats the plastic and you get something like this...



That was my second switch to melt like that.

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Old 06-10-2010, 10:09 PM   #2
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Rather than using a relay for all four settings, I opted to use two relays for the two higher settings. I found them cheap on this website:

PROLINK® SPDT RELAY WITH METAL BRACKET - DLCparts.com - DLC Parts -

They also sold the matching sockets:

PRE-WIRED MINI-GIANT SOCKET 12 LEADS - DLCparts.com - DLC Parts -

For tying into a 12-V source, I used a Bussman add-a-circuit that plags into your fusebox panel behind the glovebox. You can pick these up at any Autozone.

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Old 06-10-2010, 10:23 PM   #3
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I replaced the melted switch with a replacement I got from Partstrain.com.

Next, you want to look at your individual relays and figure out what will connect to what. You want to connect them like this...

Relay terminal #85 - 12v from Accessory On (new 16 gauge wire)

Relay terminal #86 - low speed cut wire (from fan switch)

Relay terminal #87 - low speed cut wire (to resistor block)

Relay terminal #30 - ground (new 12 gauge wire)

On the Prolink SPDT relay, that means the center plug (87a) will not be used.

Having established that, I set about connecting the 12V source from the fusebox behind the glovebox...

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Old 06-10-2010, 10:29 PM   #4
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I chose the 10 AMP "Radio 10A" location on "Box 15". Pull out the red 10AMP fuse and replace it on one of the Bussman Add-a-circuit fuse sockets. Buy yourself another 10 Amp fuse and place it on the second Add-a-circuit slot. Then plug the Add-a-circuit into "Box 15" fuse location as shown...

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Old 06-10-2010, 10:40 PM   #5
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Using new 16 gauge wire (shown as single blue line on the top of the following picture, coming from the open dash), connect the Bussman Add-a-circuit wire to relay terminal 85, which in my case, ended up being the white wire from the prewired socket I bought with the relay.



You can see how I used the white wire from the other socket to daisy chain to the adjacent relay's terminal 85.
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Old 06-10-2010, 10:50 PM   #6
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Next, you want to connect the ground. I chose the thick grounding cable from the radio as my ground. Using the sockets' prewired lines that extended from the Terminal 30's (shown in blue), I tied them to the ground cable. Note in this picture, I was initially a moron for threading the ground cables through the open radio bay. Don't be dumb like me and make sure they are coming through the HVAC panel.

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Old 06-10-2010, 11:00 PM   #7
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Ok, getting to close to cutting time... you will not need anymore of the 16 gauge wire from the prewired sockets, so be sure to pull the unused (yellow from previous picture) wires and their tabs from the insides of the sockets.

Using new 12-gauge cable, the unused tabs from the sockets, and some soldering, I made the four following cables to be used to connect the factory wiring to the relays.

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Old 06-10-2010, 11:15 PM   #8
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I started with the wiring for the "High" setting. On my Jeep, this was the thickest one colored brown and tan. If you have a acces to one, I would check with the Service Manual wiring diagram. You can find one at this link, hopefully it applies to your model year TJ:

http://forums.jpmagazine.com/70/6443...out/page2.html

Note the "BR/TN" under C7... brown and tan

Cut and strip the "high" wire. Insert the tabs from your (red in pictures) new 12-gauge cables into the socket holes corresponding to Terminals 87 and 86 as shown:



Note that Terminal 86 connects to the switch and Terminal 87 connects to the cable bundle from the dash(Which goes to the resistor).
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Old 06-10-2010, 11:26 PM   #9
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Now, I will do the same thing to the "medium high" wire with the remaining relay. In my Jeep, it was the light blue wire.



When everything is finished, it will look like this...

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Old 06-10-2010, 11:30 PM   #10
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I hope this helped. Although you don't have to, I soldered most of my non-tab connections. Something to consider.

Special thanks to "ftgiles" from the JP magazine forum. Good luck!
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Old 06-10-2010, 11:43 PM   #11
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I like your post, Im going through the same process with mine only at my vacuum switch, Ive noticed that these wires get really hot when on high speeds and dealership said that this problem has been fixed in all the aftermarket model blowers. But who wants to pay out all that money when theres is still working. There should definately be a recall for this problem because if your a TJ owner chances are your gonna have some burnt wires, switches, dashes, garage, or house at some point. Wish I knew a daimler complaint line #
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Old 06-10-2010, 11:46 PM   #12
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By the way I thought at first that I would have to buy the 3 switch control board when vacuum switched burned up, but morris 4x4 had"m and all other components on a diagram and I got vacuum switch for $20.
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Old 06-10-2010, 11:49 PM   #13
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Quote:
Originally Posted by jstephens7 View Post
I like your post, Im going through the same process with mine only at my vacuum switch, Ive noticed that these wires get really hot when on high speeds and dealership said that this problem has been fixed in all the aftermarket model blowers. But who wants to pay out all that money when theres is still working. There should definately be a recall for this problem because if your a TJ owner chances are your gonna have some burnt wires, switches, dashes, garage, or house at some point. Wish I knew a daimler complaint line #
Thanks!
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Old 06-10-2010, 11:51 PM   #14
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Oh one last thing, probably obvious to most of you...

PLEASE DISCONNECT THE NEGATIVE TERMINAL ON YOUR BATTERY before doing this or any kind of electrical work on your Heep.
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Old 01-06-2011, 01:13 PM   #15
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Just Tried This

I just tried this fix, but as soon as I turn the switch on I am blowing the new 10a fuse in the add a circuit...what am I doing wrong? I have double checked my wiring, I have the ground going to terminal 30, the new 12v from the add a circuit going to 85, 86 goes to the switch and 87 goes to the resistor block. Is it possible that I have a bad ground or did I screw something else up?
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Old 01-06-2011, 02:02 PM   #16
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It sounds like you are drawing more current in that bus than what it is rated for. Have you accidentally plugged your add a bus to a 20A socket behind the glove box? In my TJ, it was the number 15 Box for the radio (refer to the fourth picture, I used a second 10amp fuse to run the radio as well). Check the diagram below it to see what it corresponds to in your Jeep. If this is not it, then the jump in current is being caused by a short somewhere. I would then check your connections and make sure they are isolated with electrical tape or dielectric grease. Good luck, man.
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Old 01-06-2011, 02:09 PM   #17
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Clarification

Just for clarification... I put in relays on hi, med-high, and med-low. I have the 12v (16 gauge) wire coming in from the add a circuit, which I put on space 15 of the fuse box (Radio). I wire nutted this to the three wires from the relays on terminal 85. I also wire nutted the 3 grounds (terminal 30) to the line I ran to the ground, which is 12 gauge, and attached it to the tub on the drivers side. I then cut the three wires from the switch and ran as directed, switch side to 86 and resistor side to 87.

I have no idea why this is blowing the fuse in the add a circuit, but I must have done something wrong, and I am sure one of you guys will know the answer. If I remember how fuses work they blow when there is a short or too much current being drawn. I can see all of the involved wires and it does not appear anything is shorting out. I don't know how it could be drawing too much current at the switch unless I wired something incorrectly. I am not very good at this electrical stuff, so please any suggestions would be great! I do not have a voltmeter and dont really know what I am looking for if I did, so if thats the solution please be patient with the newbie!
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Old 01-06-2011, 02:50 PM   #18
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Quote:
Originally Posted by Crawdaddy24 View Post
... I have the 12v (16 gauge) wire coming in from the add a circuit, which I put on space 15 of the fuse box (Radio). I wire nutted this to the three wires from the relays on terminal 85....
I think(?) I have found your problem. If I understand you correctly, you have taken the three wires from each terminal 85 and connected them directly to your 12V source. What this does is triple your current draw (called parallel circuits). Instead, what you want to do is hook your 85 wires in series or what is commonly referred to as "daisy chaining".

What this means is this... If you look at the picture below:



Notice how the 12V wire(white wire black-taped to blue wire coming from the dash) goes into one Terminal 85 and then from that same slot goes to the next Relay's Terminal 85? Since you have three relays, you should continue the "daisy chain" by adding another wire from the terminal 85 of the second relay to finally in the terminal 85 of the third and last relay.
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Old 01-06-2011, 02:54 PM   #19
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Thank you Sir

I knew I was messing something up,,, I will try it when I get off work and I am sure you are correct...Thank you so much for the quick response. Brand new member here, just getting in to the Jeepin thing and this site is awesome for idiots like me!
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Old 01-06-2011, 02:58 PM   #20
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Also, you may want to ground each ground cable individually like I did, unles the single gound wire you wire-nutted them to is suffeciently thick enough to carry your current. I used the silver radio ground wire as my ground (The thing the two blue wires are attached to).

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Old 01-06-2011, 03:00 PM   #21
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Originally Posted by Crawdaddy24 View Post
I knew I was messing something up,,, I will try it when I get off work and I am sure you are correct...Thank you so much for the quick response. Brand new member here, just getting in to the Jeepin thing and this site is awesome for idiots like me!
Anytime man, we are all still going through the learning curve.
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Old 01-06-2011, 06:20 PM   #22
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I'm not sure if this is relevant to the fuse blowing, but the fan relay wire going to the back of the climate mode switch is 12 gauge. When the fan is on high, it requires a 12 gauge wire. If I read correctly, you are using 16 gauge.
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Old 01-06-2011, 07:03 PM   #23
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Quote:
Originally Posted by pokey View Post
I'm not sure if this is relevant to the fuse blowing, but the fan relay wire going to the back of the climate mode switch is 12 gauge. When the fan is on high, it requires a 12 gauge wire. If I read correctly, you are using 16 gauge.
He is right. You should be using 12 gauge wire for this:
Quote:
Originally Posted by chop110 View Post
Ok, getting to close to cutting time... you will not need anymore of the 16 gauge wire from the prewired sockets, so be sure to pull the unused (yellow from previous picture) wires and their tabs from the insides of the sockets.

Using new 12-gauge cable, the unused tabs from the sockets, and some soldering, I made the four following cables to be used to connect the factory wiring to the relays.

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Old 01-06-2011, 08:33 PM   #24
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Wow!!!

I thought I was the only one - my fan only works on high, and in Wisconsin at this time of year, it never leaves that setting anyway.

You did Yeoman's work on this post - thank you very much. I plan on doing the very same thing to my newly acquired '03 TJ.

It's my first Jeep, but I'm very familiar with wrenching on vehicles - ('79 Scout, '73 Challenger, etc, etc).

I did have a couple of questions, though. I haven't picked up a Haynes Manual yet, but how do you access the switch panel (get it out of the dash)? It looks like mine mounts from the back (the flange of the decorative panel covers the switch assembly). Does that whole center section have to come off? Also, what's the history of this issue actually causing a fire? I hate wrenching in this weather, and I was hoping to nurse this along until the temperatures got north of my age. Can I wait until spring has sprung?

Thank you again for this informative post - I'm soooo happy to have found it. I was originally going to take it back to the dealer, but odds are, they would've charged me for it and, they would've just replaced the switch - and that would not have addressed the real issue.

Awesome work!
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Old 01-06-2011, 09:04 PM   #25
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79Scout: To take apart the dash, follow Step two of this writeup:

Jeep Horizons :: TJ Stereo Install

To take apart the Climate control box, follow DistortedTJ's instructions on this link:
http://www.wranglerforum.com/f5/heat...rol-16174.html

As far as actually causing a fire, I have never heard of anyone having a torched Jeep because of it. At most, people seem to be getting melted switches and blown resistors.
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Old 01-06-2011, 10:03 PM   #26
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Thanks, again. I'll wade my way through this, and I always love learning new stuff.

This has now become my new favorite bookmark. You guys are awesome.
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Old 01-22-2011, 10:24 PM   #27
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Quote:
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I did have a couple of questions, though. I haven't picked up a Haynes Manual yet,
don't waste your $$, either put it towards an FSM(field service manual) for your model yr-check ebay, or the ele version also avaible on ebay or from some members on here.(search or start a thread)
the haynes is too generic for any useful info. tried mine to find the tensioner for my fan belt(several different variations) when i 1st got my jeep. ran out to buy one and my type was not even mentioned. looked all over the net and ended up buying the ele version off ebay for $3, then the printed manual w/companion drv train manual for $45.
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Old 01-23-2011, 01:14 PM   #28
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don't waste your $$, either put it towards an FSM(field service manual) for your model yr-check ebay, or the ele version also avaible on ebay or from some members on here.(search or start a thread)
the haynes is too generic for any useful info. tried mine to find the tensioner for my fan belt(several different variations) when i 1st got my jeep. ran out to buy one and my type was not even mentioned. looked all over the net and ended up buying the ele version off ebay for $3, then the printed manual w/companion drv train manual for $45.
Thanks, robbiecc - I've since gotten the electronic version of the FSM from a friend that also has a 2003 TJ. You're right - I thumbed through the Haynes manual at our local F&F, and it was uselessly generic.
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Old 10-18-2011, 08:55 PM   #29
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TJ Blower Switch (Fan speed switch)

Yeah these stupid things go out regularly. The funny thing is that you can get them at any auto parts store for cheaper than going to the dealership, but they aren't listed under Jeep Wrangler. If you ask for the Blower switch for a 2000 Chevy s-10, GMC S-15, Chevy Blazer, GMC Jimmy, or Oldsmobile Bravada, its the same switch. There is a resistor fix JP magazine did in October 2007 in an article called "retardent." I've taken the liberty of uploading it.. Here is a link to the coveted article.

Multiupload.com - upload your files to multiple file hosting sites!

Enjoy.
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Old 01-23-2012, 09:43 AM   #30
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maybe this is a dumb question but does this set up with only the 2 relays still allow selection of all speeds of the blower?

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