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ATC conversion champs help a poor soul?

4K views 28 replies 6 participants last post by  allenbradley 
#1 ·
Hey guys,

So my A/C light won't go off, still beeps when pushed, and still engages/disengages the A/C (which works) but I can't ever tell where it's at due to the constant light. Decided to jump ship and do the ATC conversion. Had all the tutorials pulled in a browser and school got in the way for a while. I have the new head unit for the mod in hand so far. Decided to get it done and found virtually all the tutorials are gone from the net and it seems this is a dead wish within intrepid enthusiasts (which hopefully aren't extinct). Does anyone have a guide or the original guides that could be brought back from the dead for this poor chap? I would rather hack and splice than pull the whole car apart. The car likely isn't going to last until the second coming, but would like to let her grow old and die with all the add ons she never got from the factory. Any and all substantiative help from charitable men would be greatly appreciated for us both.

(I have a 2004 Intrepid SXT by the way [p.s. The original Mopar battery just gave up the ghost at 174,000 miles and 12 years of faithful service!])
 
#2 ·
I don't have the clean harness-swap How-To (which I did on my Concorde that had MTC), but I did save the wiring-hack How-To as a .mht file to my hard drive.
 
#4 ·
You're welcome.

.mht is viewable in Internet Explorer. But I'm not sure that all browsers can open it, so I just saved it to pdf, so I can send you that and there won't be any problem opening it. PM me your email address - munge it so bots can't read it.
 
#5 ·
I would get the appropriate year dash harnesses for the car you have. There's two of them. Upper/Lower. 1998-2001 or 2002-2004. Can come from an Intrepid, 300M or Concorde.

You'll need the ATC Head and the Blower Motor power module also. This is the easiest way to insure a clean install that will work.

Otherwise it's cut/splice/pray.

With the dash harnesses route you'll have to pull the dash out. A lot of work but in the end you'll be Golden.
 
#7 ·
Thanks everyone for your time and help! The guide looks great. I would prefer to do the dash pull, as recommended above, but without the guides I think I may have to just do some careful soldering and shrink wrapping. You both are rock stars for being willing to share your knowledge with me. Thanks.
 
#10 · (Edited)
The blower module is mounted on the underside of the HVAC assembly (passenger side) - just above where carpet meets firewall. The part of the module that is visible is a rectangular shape, with one screw on either side that attach it to the HVAC case - see ebay links below. The screws are somewhat difficult to get a wrench on - pull the carpet back to give some room for a small (1/4" drive) socket and ratchet. IIRC, pretty sure it takes an 8mm socket (5/16" works fine too - 5/16" and 8mm are *very* close to the same size). A universal and extension may help. Like I said - very close working space.

What the blower modules look like:
(chrysler, dodge) (LH, 300m, concorde, intrepid) blower (resistor, power, module) | eBay
The ones with the metal cage with round holes is the MTC resistor that you have now. You only see the black rectangular part with it installed. The metal cage part is up inside the HVAC assembly. The ones with cast aluminum heat sink are the ATC power module.

I *strongly* suggest buying the ones with the two large round transistors on them - like this one:(chrysler, dodge) (LH, 300m, concorde, intrepid) blower (resistor, power, module) | eBay
They are pulled from 1st gen. LH cars - are much more rugged than the ones that came in 2nd gens. The 2nd gen ones are known for burning out. The 1st gen. ones last forever, and are plug-n-play into our cars. Worth the 50 bucks (or pull your own for probably a bit less if you have 1st gen. LH cars in a yard nearby).

PM me your email address (munge your address to avoid the spam bots), and I'll send you the pdf of the How-To.
 
#11 ·
I just happen to have two of those 1st gen blower modules laying around! Ready for sale!
 
#14 ·
Hey y’all. So the typical overworked dad has collected some of the parts, received the .pdf instructions (thanks Peva!) and ripped apart my car to finally try and get this done. What I am facing is the purchasing of the resistor. No junk yards around me have these cars anymore for some reason, and eBay isn’t any help in purchasing harnesses, now that I have a loose idea of the car’s anatomy, so to speak, from my current rip down. Unfortunately, the guide Peva so generously provided is not of the “hack and splice” method but the “get the harnesses” method. As getting these harnesses seems impossible at present, I am in a bit of a predicament. I have the ATC head module and the sun sensor. The blower motor resistors come in a single hardware unit deal of ~$25 or that with the plug stubs to the resistor as well for ~$110. I really would like to just splice new wires and jury rig this thing to have the features and get a bit more comfortable use from the car before I finally let her rest. Is there anyone who could provide any information on how to splice in and complete this job without being able to procure harnesses? I did find another post where intrepicon? listed some confusing wiring information that seems incomplete, at best, and unclear. He said he would post a “how to” when confirmed working, and only seems to have confirmed it working. Please help, anyone, if you can, as my back seat is full of plastic covers and I am praying for a pro to weigh in!

-Brandon
 
#15 ·
Not sure what you're talking about Resistors for. The ATC is going to use a Blower Control Module in place of the Blower Fan Resistor pack you have now.

I don't have any of the cut-n-pray instructions but I don't see why you couldn't figure out what's needed from the wiring diagrams in the 2004 FSM.
 
#16 ·
You'll also need the connector and some wiring harness for the ATC head. That connector is different than the MTC. You'll also need the connector and some wiring harness for the Blower Control Module. Same reason it's different than the MTC.
 
#17 ·
Hey thanks a lot Ronbo. Yeah that was one of my main questions was if the blower motor control unit needed a harness as well. Sort of a dumb question I guess. Looks like I will take the plunge for the $115 option that has the plug stubs at least unless the connector itself from the original mtc resistor will plug in, but needs wires rearranged to run. If I only knew the pin out..

In one of the tutorials, I believe the one PEVA provided (which seems to be the exact same instructions as what everyone has followed in the past) says to remove the mode selector wire (the one that plugs in up near the factory amp). Does this mode selector wire (the plug has two wires) need to be replaced in addition to all the other things that are obvious and/or already mentioned? I have the ATC head, the ATC plug with a few inches of each wire, the sun sensor, and still need to get the blower motor control module and figure out how to wire it.

None of the tutorials mention the sun sensor so I have to figure out how to install that and hope a wire is laying beneath it inside the dash.

Peva mentioned to check and replace the evaporator if it is leaky, but I have no idea how to know if it’s leaky. Perhaps this just means the puddle of water that forms on the ground when the car is idling?
 
#18 ·
i don't have a clue what you're talking about. I don't have those instructions so I can't verify what it says needs to be done.
 
#20 ·
I found the file I sent you, and it is the correct one.

I think some clarification is needed on the two methods. Ron already covered much of it earlier in this thread.

The "clean" method requires pulling the dash to replace the instrument panel harness with one from an ATC vehicle. The extra work in that method is in removing the entire dashboard. As Ron pointed out, the reason to go to all the trouble is that the ATC harnesses (separate from the instrument panel harnesses) will plug into the instrument panel harness that came from an ATC vehicle - no splicing, everything will be factory.

The "splice" method adds the ATC harnesses but uses the existing instrument panel harness made for MTC. You don't have to remove the dash, but you do have to do some re-wiring to make up for the differences in the two versions (MTC and ATC) of the instrument panel harnesses. That is what the document I sent you tells you how to do.

As far as the sun sensor, I believe the MTC instrument panel harness has the connector on it already, it's just not hooked up (because some vehicles with MTC and certain accessories also required the sun sensor). After making all the wiring changes in the instructions, and installing the sun sensor, it should work. You'll see an oval outline on the top surface of the forward dash trim panel for the sun sensor to poke through from underneath once you get the sensor installed. Just drill through that oval and use a Dremel or jeweler's files to shape the hole exactly to the outline, and it will look factory after the trim panel is laid back down. If I'm right about the sun sensor connector, you should find it in the cavity where the sun sensor goes - unused until now.

The fact that the instructions list the sun sensor in "Parts Needed", but don't mention it in the wiring supports my thinking that the connector is already built into the MTC instrument panel harness - you just have to plug it in. You might have to find/buy some screws to mount the sensor - easiest if you got the sensor with the screws.

(Ron - I emailed you the instructions a few minutes ago.)
 
#21 ·
Some of the earlier cars had the Sun Load Sensor wiring in the harness even if not equipped with it. By earlier, I mean prior to 2002 vehicles.

I'm going through the document you sent and I wouldn't even attempt this hack job myself with my experience on LH cars. I'm guessing the "Mode Select" wiring is the lower dash harness to what would be the Blower Control Module but can't tell from the description or crappy pictures. I'm also thinking that document assumes you have a good chunk of the ATC wiring salvaged from a yard car. Otherwise you'll be splicing wires all the way over to the BCM fro the ATC head, etc.

Good luck with the project.
 
#22 ·
It would be best if you could find the Lower Dash Harness for an ATC car with the Blower Power Module. It would be plug and play at the C202/C203 connector on the main Dash harness. The rest of that harness goes to all the door actuators on the HVAC and the Blower Power Module or Resistor Pack depending on ATC or MTC. That would save you almost half of the cutting/splicing BS.

TGS has LHS car he was parting. Might have that stuff. Send him a PM.
 
#24 ·
Both ATC and MTC "Lower Dash" harnesses have the same connector at the center dash and all the door actuator connectors. Difference is the connection at the Blower Power module for ATC or the Resistor Block for MTC. That's why I say get that harness and the Blower Power Module from an ATC car. Remove the MTC harness and Resistor block and plug the ATC stuff in. Easy-Peasy.
 
#25 ·
Looks like you'd still need to splice 8 wires from the newly installed ATC head over to various connectors on the BCM and Junction Block.
 
#27 · (Edited)
Thanks everyone. I followed tutorials on here to salvage pins from junk yard BCM plugs and did a partial harness swap. I took everything from the big white plug immediately behind the center console over to the glove box area. I do know that the ATC system doesn’t use a resistor like MTC cars do, but my original question was meant to ask if the plug to the MTC resistor would fit in the blower control module. It doesn’t, as I found, but this was provided in the partial harness swap. The mode selector wire I spoke of earlier that you didn’t know about Ronbo, is just a plug that goes into the far right passenger aspect of the HVAC/blower box that is nearest to the factory amp and is a motor that controls some aspect of the blend door. The tutorial I was following mentioned it, and removing it, simply because you have to for the harness swap that the tutorial Peva sent me concerned. I had thought initially that this tutorial being the “hack and splice” method required no further harness components other than running new wires. It turned out to be a very unclear version of what I ended up doing. It provided no clarity in it being a partial dash harness swap, so I was really confused for a time. Everything works beautifully. Thanks to everyone on here for helping out such an old and continual question. Glad to have it done.
 
#28 ·
Congratulations on your persistence in making it work.

Being as I ended up doing the conversion the “clean” way (as explained earlier, since removing the dash served double duty in allowing me to also replace the leaking a.c. evaporator), I wasn’t forced to make 100% sense out of the How-To that I sent you in my cursory reading of it. My guess is that it didn’t make total sense to me in reading it thru, and that my (apparently incorrect) assumption was that it was one of those things that would make sense while actually doing the work it describes. From what you’re saying, that wasn’t the case, and you had to fill in gaps that were left out or were not detailed adequately.

Again, congratulations. Now you can just enjoy the results and let the memories of what it took to do it fade away like a bad dream. :)
 
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