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drcomanche

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About drcomanche

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    Comanche Aficionado

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    Lusby, MD

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  1. Which diagrams do you have? I'd like to include all possible info for everyone, so if its different then it would still be handy for people with pre 91 harnesses. I'm looking at the Haynes manual, and it is equally as confusing, but seems to have the relative same circuits for the relay.
  2. According to the Haynes manual(which I'm not sure how reliable it is) there are 3 wires going to the ECU from the HVAC harness. The power input is the Blue White wire to the 4 pin relay. The only one from the cab that interacts with the ECU is the white green wire that passes through, but before it gets there, it divides to the relay and the low pressure switch. Its inclusion in the relay is what dictates the compressor clutch engagement. The rest that connect with the ECU seem to feed out to the other components. I reiterate that the Haynes manual has wires that don't exist on any of my 3 harnesses(91, 93, 96) so this is what I've gleaned from looking at the physical harness and the diagram. I figure the only thing the compressor needs from the harness is a single signal for when the interior selectors choose AC to engage the clutch. I say all of this mostly in speculation, since I can't start my vehicle and volt check it. I'm trying to understand the wiring to the best of my ability, and this just seems to be the most likely solution. I'm open to broadening my scope with more info so that we can have the most complete manual for installation.
  3. Apparently, from what I've heard, newer age compressors don't draw as much power, so it doesn't need the extra idle rpms. I'm not sure how true that is, but it's something to consider.
  4. I've seen another plug with almost the exact same fitting type, so maybe that relates to the dealer installed side. It's a 2 pin connector with only a tiny difference in the internal shape. I'd be curious to see how the pre 91 harness looked. If you have some pics or more info on that, I can add it to the main post so we can compile everything. The best I can guess is that when the ac kicks on, it triggers an idle adjustment for the extra load. I'll have to ask a buddy who's more well versed in the programmed side if it does more. Judging by the system, it doesn't seem to need too much from the ECU. The rest of the wires that go through the block seem to go to the relay or the blower motor. Only the green wire hits the ECU.
  5. This will be a thread to compile all the information about adding AC to non AC equipped trucks. I know there is another thread started almost a decade ago, but it seems to have very little info on the subject. Eventually, this should turn into a write up to settle all of the questions and technical info into one place. If you feel like I've missed something or want more info on a specific application, I can try to look into it and figure it out as well. This is for all the information, so I will edit the original post as we go. For background, I have been taking apart a bunch of stuff on the truck(as per my usual winter tradition) and while I had the dash out I figured, why not add AC? It can't be that hard. In terms of mechanical difficulty, it isn't. The electrical became a huge issue, on the other hand. Anyone with enough mechanical skillset to remove their dash should't have too much issue installing this. Obviously, the easiest way to add AC is to get a system from a matching year donor vehicle, that was you won't have to troubleshoot wiring. I chose a 96 because it was available to me for cheap and it is an r134 system, making it easy to charge and deal with. The parts I grabbed from the donor were: Compressor Evaporator(the "radiator" in the HVAC box) Condenser(the "radiator" behind the grill) Drier Expansion Valve Suction Hose(Compressor to Valve) Discharge Hose(Compressor to Condenser) Liquid Hose(Drier to Condenser) Hose(Drier to Valve) Low pressure switch(attaches to Drier) HVAC airbox(AC equipped airbox assemblies came with a larger compartment space to fit the evaporator) Dash harness(My truck wasn't equipped for AC, so there were no wiring components in the harness) HVAC Controller(the in dash selectors) *These parts can change depending on what years you are scavenging parts from. I believe some systems had an accumulator, too. I took all of my parts from a 96 Cherokee. Installation of the engine bay components is fairly easy, using pre existing bolts and holes. Non AC equipped trucks will have to remove the dash and replace the internal airbox with an AC optioned one. If you're looking, I recommend going to a pull yard and taking the whole system, that way you know you have everything and know it all fits together. The wiring is the tough part of this one, so based on my experiences, I've created a few diagrams to help make it possible. The Haynes manual was of some help here, but it was lacking in some of the wiring bits, which makes it all the more confusing. The wiring itself is a small grouping. I chose to dismantle the entire harness to separate it as completely as possible rather than cutting and trying to build it. This involves removing a few pins from the firewall plug and one from the fuse block. The firewall plugs require you to remove the retaining pins before they can be removed(plastic bars on the side of the block). Then just use a 90 degree pick to work it out of the hole. The fuse block side has 2 metal prongs on either side holding it in. I used the pick for this as well, and with a little manipulation got it out. The rest of the circuit is attached only to these 4 wires. The black and tan wire is the power in and splits into 2 wires(also black and tan) that feed into the same plug, but 2 different switches. This feeds the sliding bar selector on the dash unit. From there, it has 2 light green and white wires that exit, one going to the firewall plug and turning into a green wire that feeds the low pressure switch, the AC relay, and the ECU while the other goes to the thermostat plug attached to the HVAC box in the cab. The last wire(yellow tan) goes to two different locations, the first being the blower motor selector switch on the dash unit, and the second to the blower resistor on the HVAC box in the passengers footwell. The blower switch simply controls the blower fan speed with a green wire going the the firewall plug(and off to the blower motor itself). The thermostat plug itself grounds to the harness with the black wire and sends a blue orange wire to the firewall plug(I'm not sure if it's any different to have it ground to the metal dash structure as opposed to going through the dash harness). These are the only wires in the circuit and should run the entire system. According to the Haynes manual, this should be how 91 to 96 works. The earlier 87 to 90 is very similar, with differing colors for wires. The main input plug. This feeds the whole system in the cab. The blower switch plug. This selects the speed of the blower fan The thermostat plug. Sends one wire out and grounds to the dash harness. The blower resistor plug. Controls fan speed The 4 pins. In the engine bay I found something interesting. Despite my new(to me)harness from a 91 not have AC equipped, the engine harness still has the components for it. It has an attached low pressure switch plug(that I'll have to replace with the one on a newer harness, but uses the same color wires), and the AC relay, rather than being empty, is fully wired, so I believe the ECU is equipped to handle AC even if the cab harness is missing the necessary parts. I won't know for sure until I start the vehicle, which is going to be a long while, but I can't see any reason it wouldn't. The AC relay has dedicated wires that are only part of that system that route to the ECU. Any questions or additional info, let me know.
  6. I'm going to start a new thread on the technical info for the swap to eventually become a write up. I have a good bit of the information for it so hopefully it can help those that don't have a direct donor to pull from.
  7. I suppose I should have clarified more, but yes, cut the braces the po made as close as possible using a metal cutting disc, then use a flapper wheel/grinding disc to eliminate the rest. I tend to generalize a bit when talking about "grinding" to anything that I use the angle grinder for. I hardly ever use a grinding wheel when there are better alternatives.
  8. Judging by your cross member, looks like you have a long bed truck. The rear of the frame only looks like he welded tabs, which will be easy to grind off. We will need to see the forward portion to know if he hacked anything up there, as there are 2 bolt points that stick above the frame. Otherwise, it looks pretty untouched. In the third picture, though, I do see some rust poking through. May want to address the inside of the frame before mounting a new bed. Or if you're going flatbed, cut the whole thing and build a frame for the rear. As far as putting a new one on, have a buddy help you carry and place it. It's only held down by 8 bolts and the fuel tank. I've even worked my way around doing it myself.
  9. I'm currently in the thick of it trying to install a system from a 96 XJ on mine. I'd be fine starting a new thread on it where we can discuss all the technical stuff(so we stop beating the proverbial dead horse). From what I've researched, wiring wise, it's not too complex a system to get into and usual just feeds back into itself. If I can manage to pull it off, I'll make a write up for it, but having another thread to bounce ideas around would be beneficial as a technical talk section.
  10. There was no other brake components on it since I've had it, so no distribution block or anything. I figure I'll grab the xj model which does rear brake distribution at the block vs the mj which does it at the load prop valve and then also have a dialed valve for the rear. I'll try to get one with a sensor, as having a warning light would be useful.
  11. I forgot that the mj had a load prop valve. In my case, there is no valve. All I had was an adjustable valve in the engine bay with a single line to a t fitting on the rear. It makes sense for me to have it, since mine doesn't haul anything but a spare and a fuel cell. It's strictly for fun, so it won't be filled with anything more than that.
  12. So the short story is, I'm switching my braking to a dual diaphragm booster to stop the monster tires. When I took it out, I saw that the front brake line just went to a t connector and then hard lined to each sides ss to caliper. The rear was a single adjustable prop valve(that was seized). Because this is how it's always been, I never thought much of it, but I've also never had ideal braking characteristics(it tends to sway back and forth under a heavier brake load). I'm not sure if that is due to the uneven distance the fluid has to travel for one side or if the lines hold an equal constant pressure. After researching some, I found that there's generally a proportioning valve that mets out brake pressure. My question is, is that necessary? Will I have better braking results by adding that back into the system? I researched on here and found a thread discussing internals and ideal setups, but that was all with relatively stock brakes. My Jeep runs on a d44 9 inch axle combo with the large disc brakes. I really don't know if that makes a difference.
  13. Thanks, I'm working on a writeup for them. I've had more than a few requests on how they were done. And now some pics of the shows from OC And a little flex when I got back.
  14. Thanks, still rolling and giving me hell while it's at it. It's come quite a ways since the days of old. Another big update, since I always kind of fail to get back to this build thread. So after all the prep for this show, I decided I was going to take it out to Ocean City Jeep Week this year. To do so, I needed to get it geared up and ready for a 3+ hour trip out there. Mainly, I needed some quality of life fixes for it so that I could survive the trip with my sanity and my health. The most pressing matter was to figure out what the heck was causing all the noise in my front axle when it was in 4wd. I removed both hub rotors, spindles, and knuckles to get into it. I figured, even though there was hardly any miles on the set of wheel bearings in there, I would replace them since I'm there. When I took everything out, I did find some interesting things with the spindle. The noise was my outer axle shafts pushing against the bare metal of the spindles. For some reason, they had some play that allowed them to contact which ate about a quarter inch out of the drivers side spindle. I mulled around ideas for a bit and tried to diagnose it, but came up with nothing. The turning should re center the axle shafts at the ball joints anyway. Well, eventually I found my answer while prepping the inner and out shafts(rust removal and some paint). Turns out, the ones that came with the truck were, not only, the incorrect sizes (came from an ifs bronco making them a half inch longer), but were also 2 different shafts themselves. I bought new chromoly outers and put them back together. While I was there, I did notice some water in my diff when I drained it. The seals seemed fine, so I'm going to chalk it up to poorly placed axle breather, moving shafts, and all around poor quality control on my part when I scrambled it back together before. I painted my diff cover and did some small welds on my old breather port to better seal it. While I had the axle dropped, I adjust some axle placement and painted up my bump stops. I fixed my spring retainers so they weren't bent and finished painting all the steering linkage. Another big problem was that the engine, while it ran, would have a sporadic miss at idle and while driving. I replaced every remaining sensor on the engine except for the cps, and nothing was able to fix it. All new injectors, spark plugs, everything... To help combat the heat in the engine, I ended up replacing all the hoses, sensors, and housing for my cooling system. It hadn't been done since I got the truck, so it couldn't hurt to do it now. I also did an oil change while I was at it after a bit of debate. I should have done a transmission fluid change for reasons I will talk about later. I also wanted to have a stereo for the trip which presented its own challenges. The old stereo wiring was rigged up poorly(just enough to work with the old setup), so I had to get back into my wiring AGAIN, and figure out what was up. Took some real troubleshooting, but I got it to work eventually. Had to custom make a bracket for it too. I rebuilt my rear driveshaft to, hopefully, get rid of some of my vibrations. This also meant I could take the time to repaint it while it was out. The last thing I wanted to get remedied was to wrap my exhaust downpipe to keep some of the heat out of my floor boards. Long trips tended to cause some extensive heat sink into and through the floors. That was another simple project. So the time came and I drove out to OC. The trip out was surprisingly easy. The driveshaft rebuild eliminated a ton of vibration, but the unbalanced wheels did still cause a bit of trouble. It was a nice high 70s day, so it made the temp very nice. Everything seemed to work very well... Until I made it there. As soon as I entered OC, I noticed that it was a bit difficult to get into gears. The engine also started feeling the heat, causing the #3 injector heat soak issue. With those issues, I was still pretty close to my house, so I made it fine. I let the truck rest for a few hours and then went to the show at the convention center. It was a nightmare. There was no parking for 5+ blocks in all directions, as they didn't block the lots off for just participants. I drove for a half an hour and couldn't find a spot anywhere. I missed the deadline for the show and since I couldn't find a spot to park, I couldn't register either. Instead, I just relaxed the rest of the day fishing. I went to the show the next day, which was more of a vendor affair, and found some parking in the main lot. Lots of looks and tons of questions, but I finally found my way in. I debated on registering, since there was only one more day of it(I didn't plan my trip quite right on the time), but decided to since there would still be an obstacle course, a beach crawl, and a show. I got so see quite a few Jeeps at this one, and quite a few vendors. The next day, I played it safe. I didn't want to risk the truck overheating while trying an obstacle course(the trans was getting worse and worse, and the truck was getting hotter WAY faster), so I just went to the show as a last ditch effort to enjoy the festivities. It started out slow, but it turned out to be really cool. I met the director of OCJW while I was out there(didn't even know it was him) and he invited me back next year to put the truck on display! I also met a writer from JP magizine who wanted to do a feature when I got the chance. Then I won an award for it, so all around, a fun experience. I spent the rest of my week in OC just enjoying the weather. The trip back was far more difficult. The day was easily in the 90s. The truck heated up very quickly, and as a result, the trans heated up too. Shifting was very difficult and I had to stop in Annapolis to let it rest for a couple hours. I did an on the fly trans fluid refresh to help it along a bit. The engine was running poorly and for some reason, the charcoal canister flooded with gas. Not sure as to why, but it had to endure. At about 20 minutes out, the passenger front brake locked up and overheated 10 minutes later. I limped it back home from there. From there, the truck sat for a few weeks while I contemplated what to do next. I did take it to a friends place to test the compression to try to diagnose the engine miss. I was told when I bought it that the engine was rebuilt 15k ago. We tested all the cylinders and the results were.... 150 across the board. No fluctuation on any cylinder, so it must be somewhat true. My best guess is that something in the hackjob electrical is shorting out or poorly conducting. Now it's ready to go down under the knife again while I prep it for next year. Many things to come soon. Broken clip and rusted in. It was tough to get it apart An upcoming project Still pretty nice in there, aside from the water. Pulled hubs and spindles. A look at the damages. I pulled the bearings and replaced them with a cool hardened poly bushing from wild horses bronco. The obvious differences Primed and painted Painted driveshaft. The new and old And back together Heatshrink before taped Washed and ready In OC Awards
  15. Sorry for the late responses. I don't take it out much right now, so I don't get to test very many things. In all cases stated above, the noise stops.
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