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Air Conditioning and TIPM

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JK AC Compressor Clutch


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Repairing a Deere 317
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Repairing a Dodge Ram Air Conditioning and TIPM
(2006 Ram 2500 w/ Cummins Diesel)

May 29, 2015

During the second week of May we visited our son's family so we could watch their boys play in a soccer game. After they finished the game we headed back to their home for some lunch. The boys decided to ride with us in my truck. Being a rather warm day, I cranked on the air conditioner and set the vents to blow some air into the rear seat. The AC started cooling of the truck quickly, but stopped blowing cold air about half way through the 20 minute drive. I hit the switch on and off and didn't feel the compressor kicking in. I figured that I had either blown a seal or hose or the AC clutch coil circuit had died.

Later in the day we made the two hour trip home in a hot truck. That wasn't much fun.



This is the schematic showing the input and output for the AC clutch control coil. Since my truck is a diesel, the input to the TIPM comes from the powertrain control module.
This schematic show the second (revised) temporary AC control circuit. Getting power from the lighter circuit prevents the clutch from staying engaged when the key is off.

When we arrived home, I took the truck straight to my shop and tested the AC system. If you don't have an advanced scanner that will pull all of the diagnostic trouble codes (DTCs), you can check for power and ground at the AC compressor clutch coil. I had voltage but the compressor wasn't kicking in.

I spent the evening reading my Dodge workshop manual and everything else I could find about the compressor coil and how it is activated. What I read didn't please me much at all. It seems that the clutch coil gets its power from the fuse box. However, the fuse box is no longer just a panel with wires and fuses. The fuse box is actually named the Totally Integrated Power Module (TIPM). Instead of external relays to control things like the compressor clutch coil, it uses solid state devices. If it sees that a circuit is pulling too many amps, the TIPM can and will shut that circuit down. Apparently that is what has happened to mine.



The black C2 connector on the back of the TIPM.
Click the image to read the notes.
The blue C9 connector.
Click the image to read the notes.

When I jumped the compressor clutch coil directly from the battery, the coil was able to pull in the compressor clutch, giving me AC again, but it was is pulling 6+ amps. The spec for the coil in my workshop manual stated that it was supposed to only pull 4 amps maximum. When checking the two wires that go to the coil connector from the TIPM circuit, I was reading about 11 volts, which was within specs, but the circuit carried no amps at all. It wouldn't even light a test lamp. What I though was strange is that if I grounded one of my voltmeter probes and probed either of the two wires going to the coil connector, both were showing the same 11 volts. It appeared that something was amiss in the TIPM as well as the compressor clutch coil drawing too many amps.

I started trying to perform the diagnostic checks in the manual, but to do most of them, you need some way of reading the voltages in the system. This is done at the dealer by using the StarScan ODB scanner or similar. I didn't have one of those. There is an interesting thread on the clutch coil and a possible work-around here: While this work around wouldn't work for me as the output from the wires going to the compressor coil couldn't produce enough current to activate a relay, reading through the whole thread gave me a little better understanding of what was going on in the circuit.



An image of the back side of the TIPM showing the locations of the plugs.

C9 plug removed from the TIPM so I could isolate the wire.

I pulled out the TIPM and checked the dark blue wire with a yellow tracer coming from pin 3 of the C9 connector of the TIPM and found that I had the same ~11 volts I had at the compressor connector. This is supposed to be the positive wire to the clutch coil. The negative wire on the compressor connector appears to go through the AC pressure transducer on the side of the compressor and eventually to ground. I then checked what was said to be the trigger wire to supply power though the DB/Y wire just mentioned. This wire is on connector C2 pin 10 and is light blue with an orange tracer. It comes from the powertrain control module on the diesel model and should supply a ground to the TIPM when the AC switch is activated. I got 11 volts when I probed this wire.

For a test, I probed the LB/OR with a grounded probe. This would cause the compressor coil to activate, but not stay activated. It would pulse the clutch on, then off, three or four times and then stay off. If I removed the probe and then probed again, the same on - off routine would start again.

I tested all of the components in the system the best that I could without having StarScan and even pulled the center dash to check the operation of the AC switch. As far as I could tell without the proper diagnostic tools, everything appeared to be working up to the powertrain module or the TIPM.

We needed to use the truck the next day and it was going to be hot, so I worked up a quick and dirty switch to a relay to power the compressor. The AC worked fine in the morning, but only lasted 1/2 day. I lost the ability to turn the compressor on around noon and we spent the rest of the afternoon driving in a hot truck - or at least I did. My wife picked up her Lexus from the upholstery shop and got to drive home with AC. I had to sweat.



The wire is removed by inserting a thin screwdriver under the connector.
The wire is removed.

When I got home, I put an ohm meter across the coil terminals and it had died. Open circuit. There was nothing more that I could do at this point but to order a new coil. I ordered the coil from coldzone111 on Ebay - $45.77. The seller had great ratings and a few of the comments gave a thumbs up on this coil.

I had also done some more reading in the manual and found that every test was prefaced by making sure that you checked for trouble codes and repaired those first, then cleared the codes. I needed some way to do that. I decided on the AutoEnginuity (AE) software and dongle along with the Chrysler add-on software. My main reason was that I could add the Toyota/Lexus package for my wife's car if we needed it in the future. The AE Chrysler software would also let me pull codes from my son's Hemi Ram and his wife's Jeep JK. If I had no other vehicles to consider, I might have gone for one of the performance programmers that also pull and clear codes. At almost $500, the AE software, dongle, and Chrysler add-on wasn't cheap, but I figure it will pay for itself eventually. I sent the AutoEnginuity folks a couple questions from their contact page and was pleasantly surprised when I received an answer back within a few hours. Their support has been surprisingly good and this is something that you can't say about many companies these days.



The C2 connector has been removed and the white plastic protector has also been pried out.
The white plastic pin connector has been reinstalled

I received the coil in a couple days. Pretty quick shipping and the coil looked good. Installing the coil without removing the compressor from the truck was a pain in the butt. It is easy enough to pull the 4 bolts to drop the compressor, then pull off the clutch plate, pulley and coil, but trying to line up the coil and press it back on while on your back under the truck is not a whole lot of fun. It took a couple tries before I got the coil fully seated. An inspection mirror on a stick allowed me to look at all sides of the coil and make sure that it was seated as far as it would go. To allow me to press on the coil, I used a 1" thick ring of aluminum that I had saved in my metal scrap bin. A wooden ring about the size of the coil would work just as well. I placed this on top of the coil then placed the clutch disk on top of that and used a longer 6 mm bolt in place of the stock clutch disk bolt. I ran the bolt down as snug as I thought a 6 mm bolt could handle, then tapped on the clutch disk with a compothane "no bounce" hammer. This is a plastic hammer with metal shot inside and may also be referred to as "dead blow" hammer. Once I got the coil to move a bit, I retightened the 6 mm bolt and repeated lightly hitting the clutch disk. I repeated this until the coil was fully seated on the compressor.



There are four bolts to unhook the compressor.
Using a too-small puller to remove the AC compressor pulley. This barely worked.

I used the same technique to install the pulley. It was slow going, but I finally got it seated. I should have removed the clutch disk and inspected it and the pulley face before I ordered the coil. If I had, I would have ordered a new clutch disk and pulley at the same time. My clutch disk and pulley are no longer flat where the contact each other. There are grooves where the clutch disk has been slipping against the pulley face. I will order the new parts soon, but am guessing that the current ones will last throughout the summer.

With the new coil installed, I ran a couple wires from the battery to test it. It worked well and I again got cold air from the vents. Since I didn't know what fixing the TIPM was going to entail, I wired up a switch and relay so that I could manually control the compressor clutch from the car. This time I wired the relay coil hot lead (terminal 86) to the #40 (20 amp) fuse in the TIPM which gives power to the cigar lighter when the ignition switch is on. I wired the negative side of the relay coil (terminal 85) to a switch that I attached under the dash to one of the trim screws. The other connector on the switch was wired to ground under the dash. The power lead of the relay (terminal 30) was wired directly to one of the batteries through a 15 amp fuse and fuse holder. The power output of the relay (terminal 87) was wired to the plus side of the compressor connector. I ran a wire from the negative terminal of the battery directly to the negative side of the compressor connector. This worked well for the one day I needed to use it before my AE software arrived.

The temporary circuit to control the AC compressor clutch coil is NOT a fix that I would want to use for an extended period of time. If you need to use this circuit, you should be aware that there is no component in the circuit that will shut off the compressor if the Freon pressures become too high. A safer circuit could be made by adding a high pressure switch in place of the AC transducer and wire this switch between terminal 85 of the relay and the on/off switch. Without a way to shut off the compressor clutch coil when the system pressures rise above the recommended level (460 PSI), you stand a chance of AC compressor damage or leaks caused by too much pressure. If I was looking to make a circuit that would be used for a longer time, I would also need to find a way to increase the flow of air over the AC condenser when the AC is used when idling for extended periods of time, such as stop and go traffic.

I finally got the AutoEnginuity software. I had a little trouble getting it installed, but wouldn't have had the trouble if I ran more current Windows software. I run Linux exclusively these days. I had a couple of old laptops that came with Windows, but had been switched to Linux before they were retired. One had come with Windows 2k Pro and the other with WinXP Pro. I had decided to remove the Linux on the newer of the two and reinstall the XP software that came with it, but I couldn't find the disk. I did find the Win2K disk and since it was supposedly supported by the AE software, installed Win2k. When I went to install the AE software, it installed OK, but when I went to open the Giotto program that runs the scanner, I got an error:

ScanTool.exe - Entry point not found

The entry point is Wow64process and could not be located in the dynamic link library Kernel32.dll

It looked to me like the software was looking for a 64 bit kernel on a 32 bit machine. I couldn't find anything on the AutoEnginuity site, so I sent them an email. This was very early in the morning and they hadn't opened yet. I decided to do some sleuthing on my own. I pulled out an old desktop computer with WinXP Home version on it and loaded the AE program. This time when I went to launch it, it launched without error. Hmmm. For some reason, it looks like the software didn't like Win2k.



The compressor pulley and coil have been removed and the snout on the compressor has been cleaned and lightly oiled.
The compressor clutch disk has been wearing for the past nine years. The face of the pulley has the same wear lines. I will replace both soon.

I again dug through the last 10 years worth of CDs and this time I came up with the original XP disk for the laptop I had installed Win2K on. Rather than do a fresh install, I just ran the upgrade. About 40 minutes later, XP pro was installed. Since this had been an upgrade and not a fresh install, the shortcut for the Giotto scan program was still on the desktop. I clicked it and the program launched. AutoEnginuity got back to me a little later with a couple things to try, but I had already solved my issues. Still, having anyone's support get back to you the same day is pretty darned good.

Apparently the Chrysler add-on program is loaded from the main installation disk and that the dongle is coded to allow you to activate it. I was a bit surprised that there wasn't a second CD to load. My dongle didn't seem to be programmed to allow me access to the Chrysler add-on package and gave the folks at AE a call. While we were on the phone, I received an email with the code to activate the Chrysler package. This did the trick and once I got it activated, I was presented with more screens and options than I knew what to do with. Most of the options are abbreviated like HVAC for the heating, ventilation and AC system. I was in the automobile service industry for a couple decades and know my way around cars pretty well, but many of the abbreviations meant nothing to me. It is going to take me a while to get full use of this product.

With some help from a post on one of the diesel forums, I discovered that if you click on "Change System" to "TIPM" then go to "Test OnBoard System" tab --> "module configuration" you can pull the diagnostic trouble codes (DTCs) for that system. You have the choice of All, Current, or None. I chose current. I got quite a long list - see the images below. I realized that probably quite a few of these were from my pulling connectors during my trying to diagnose why I had no ground on the LB/OR wire on connector 2 of the TIPM. I decided that I would print out the DTCs and then clear them to see if any came back. Clearing the codes is a bit non-intuitive. The button to clear them reads Clear MIL. MIL is the multifunction indicator light. It was not on, so why would I need to clear it. However, this button also clears the DTCs. When you click it, you again have the choice of All, Current, or None. I chose Current. Once you clear the codes, you're asked to cycle the key switch to off, then on. I did this and pulled the codes for the TIPM again. There was now only one single entry about being able to communicate with the CAN bus. I figured that since the workshop manual was adamant about having the codes cleared before you tested the system, that it was worth a try to unplug the dongle and fire up the truck. I started the truck and hit the AC switch. The engine lost a couple RPMs as the compressor clicked in and I again had air conditioning. I did not clear the TIPM and am not positive that the AE software will even allow me to do this. There is an option for clearing the ECU, but I will do some more research on this before I start messing with things that I am unsure of.



This is the top portion of the AutoEnginuity ODB trouble code report I ran after replacing the compressor coil.
On the bottom half of the report, you can see all of the DTCs that pertain to the TIPM. I believe I set most of the codes while checking the TIPM plugs.

The bottom line is that for my truck which had the same symptoms as found in the worst cases of this thread:, clearing the set DTCs was all it took to get power back to the compressor plug. I have seen a couple other posts on the Diesel boards that say they have done the same thing with their performance programmers, so I am not the only one that this has worked for.

I'd like to give my thanks to the forum members over at for getting me headed in the right direction on this repair. The thread linked above saved me a lot of time trying to diagnose this issue and hopefully this article will add to the general knowledge about this repair.

On the flip side, I am really disappointed in Chrysler/Dodge/Jeep. I have read about countless problems due to too strict of parameters being programmed into the TIPM. The problems range from this AC issue, to vehicles not starting, to having a headlight burn out and having to have the TIPM system reset after you install a new headlight. What kind of company makes a headlight replacement something that has to be done at the dealership - even if a headlight replacement is a little more involved (and much more expensive) than the old "sealed beam" type headlights? I have to say that this type of engineering makes me angry. Is shutting down an electrical circuit when it gets a reading out of it's intended parameters really any better than just have a fuse pop if a circuit draws too much amperage? I guess if your mission is to overly complicate the vehicle and tie the customer to the dealership, it is.

I like my Cummins diesel a lot, but it's almost 10 years old. I have been toying with the idea of a new one. However this experience has soured me on buying a new Dodge. I can't see giving my hard earned money to any company who tells me that I need to come back to their service department and pay them to reset the system after I have replaced my own headlight.

Keeping this old truck going has much more appeal than it did last week. Also, I think it is time that I start reading up on what other car manufacturers are doing. I already hate the idea of General Motor's OnStar system tracking the owner's every move. I am hoping that I find one manufacturer out there that doesn't feel that they have the right to track me or lock me into their dealership network for simple repairs.

© Fager May 29, 2015