Klima > Ice Cube - Not Working
 

Though I am going to check my connections again (3rd time) the replacement of the Klima with an Ice Cube is not working on my '87 300TD. A fuse jumper wire from #5 to #7 makes the compressor engage yet when I put my Klima replacement in, the compressor would not engage. Any thoughts on this one would be greatly appreciated.

Following the MB Service Manual ACC for Model 124 I ran the sequence of tests "Checking compressor cutoff if the electromagnetic coupling of the compressor is not switched on." Each test returned nominal values. That brought me to "Renew control unit (N6 - Klima)." That being said, again I put my Ice Cube for Klima replacement in. No compressor engagement. Remember, in the testing sequence terminals 5 & 7 are jumped and the compressor did engage.

Ideas on what to do PLEASE.

Still moving on with this project I found -0- volts at terminal #4 of the Klima socket with the engine at idle and appropriate switches set. According to the SB link, voltage should be battery until full throttle. If I am heading in the correct direction, this may indicate that the full-throttle micro-switch is closed all of the time. If it is in fact bad, would this explain why the Ice Cube relay replacement for the Klima isn't working for me? Is there anything short of replacing the micro-switch I can do?

Can you post the wiring layout you used to build your Klima replacement? Which terminal on the car is connected to which terminal on the ice-cube?

I doubt the full throttle micro-switch is the problem with your ice-cube bypass. It would take multiple ice-cube relays to include the full throttle shutoff logic into the Klima replacement. There's a reason MB used electronics...

- JimY

Tha A/c panel must send a GROUND signal to the Klima relay for the compressor to engage. That signal comes in at pin 10 of the klima relay.

Also the tachometer must work & the RPM signal must come to the klima relay as well.

There is also an overheating switch on the engine that can stop the compressor from comming on. TRY disconnecting that switch to see if the switch is shorted.

Also on the accelerator linkage there is a limit switch that cuts off the compressor durning acceleration, try disconnecting that switch as well.

JCYUHN
Okay . . . the wiring layout for my Ice Cube (replacement for Klima) is #1 > #85, #10 > #86, #5 > #30 and #7 > #87.


M.B.DOC
The ground coming in at #10 is present i.e. battery voltage with #10 (-) & #5 (+) reads battery voltage.

Tach is working properly as is speed sensor test.

The emergency cutout temperature switch results in < 1 volt when tested at #5 (+) and #12 (-).

I am uncertain if you mean the micro-switch for full throttle as to your reference to the throttle linkage. If so, where I should be getting battery voltage at #4 of the Klima socket I get zero. Unplugging the connector at the bottom of the micro-switch does not change it one way or the other.

I am wondering if the lack of battery voltage at #4 is indicating that the micro-switch portion of the circuit is the problem. If I understand it correctly, when it operates correctly there would be battery voltage until the micro-switch passes full-throttle and cuts the compressor for extra hp. This is where I am stuck . . .

Going to talk my way through this one . . . I believe I was wrong in thinking the micro-switch is the culprit. As I view the schematic it appears the micro-switch grounds what is supposed to be the battery voltage at #4 in the Klima socket. If I am reading the schematic correctly that would mean since there is no voltage at #4 I'm heading in the absolute wrong direction. I believe I need to find where the source of voltage to #4 is and find why it is not present at the socket. On the other hand, if the voltage only gets to #4 from one of the internal sources of the Klima, with the Klima out I wouldn't find any present at #4. I doubt myself on that last statement since the SB explanation link refers to either the EGR controller or the idle controller ISC as a source of converted pulsed DC signal that drops out when the micro-switch engages at full-throttle. As I read that portion of the explanation I am probably not going to find battery voltage at #4 . . . ??? Too late to be this lost.

Try this ...
Unplug both temp cut out sw and full throttle sw circuits [ 4 and 12]
and then ground #10.

Glad to try . . . before doing so, you are saying to unplug the switches at their source and ground #10 at the Klima socket? I am trying to understand another way of accomplishing it. The only other way I can think of is to remove the socket and attempt to remove the female ends from the socket block.

#10 I believe is the compressor pressure switch
#4 is the micro-switch cutout
#12 is the temperature switch with one side (b) emergency cutout

Sound correct?

Arthur
Tried unpluging connectors at S25/5 (#12 at Klima socket) & S27/1 (4 at Klima) then grounded S31 (#10 at Klima) with no compressor engagement. All of these were done with the Klima plugged in and the connections interrupted at the individual switches.

OK
That test was to test the relay circuit and acc panel to seek ground..
Unplugging both the temp and throttle sw eliminates them [ they ground to stop comp]
Grounding 10 at relay eliminates the comp pressure circuit/panel
When you jumper 5 to 7 , you are bypassing the relay circuit..[simply jumping the load contacks of the relay]
So, you are down to relay /modual input fault

You have the schematic there ?
I am not sure if I am on the right one ....

Arthur
Just got Adelphia Powerlink back . . . read your message and was getting itchy since I couldn't let you know I have the schematic.
Steve

Me too
I was trying to trade some stocks and lost mine [ powerlink] too
Anyway, which schematic should I be looking at ??

Just so you don't have to make assumptions, my car is an '87 300TD so that is Model 124.193 with the 603.960 engine. My schematic is from the MB Service Manual - Automatic Climate Control Model 124. Though I haven't checked, I believe it is the same on the CD volume.

I went through the testing procedures for all of the Klima connections listed in the manual. Everything passed which led to the Klima (according to the manual). Since I wired the Ice-Cube according to this forum I thought it would replace the Klima and work okay. Not so.

Hope this helps show where I have been so far. I am really stumped at this point.

Thanks a bunch for taking the time to look this over for me.

Steve

I see no s25/5 , but s25/11 feed from 12.

There is an idle rpm ,min 600rpm, with a 10 sec delay input at pin2.
Do you show that?????????/

Okay. S25/11 & S25/5 as well as S25/3 are quasi same function just different engines and/or years.

My pin #2 goes to X29/4 (1-pole test coupling) and then to N8 (Control Unit - Idle Speed Control). This N8 has the K1 overvoltage relay, L3 Starter Ring Gear RPM Sensor, and two ELR related devices connected to it. Not certain how the Idle Speed Control Unit works into the overall scheme of things. Actually, I haven't even located it in my vehicle yet.

I am not familiar with that RPM circuit .
My schematic says it was phased in from 87-88..
SB prolly knows more on that [ or MBDOC]

I am assuming you do have the car running when checking the other switch disconnect test...

Yes on the running while performing the tests.

The one thing that keeps making me wonder is that where most people use the Ice-Cube Relay to bypass the Klima and solve their ACC problems, mine won't engage the compressor when it is installed. That has to be some type of indicator.

So ,
where exactly does the ice cube line up with the pin3s and which are primary [ coil] and which are contacts [ load ] on ice?

Pin #3 on the Klima socket is not used by the Ice-Cube relay. The only Klima socket pins used are 1, 5, 7, & 10. Actually, pin #3 on the socket does not have a female receiver but rather a blank hole. That seems strange to me since the Klima has a pin at #3. So the complete line-up is 1 > 85, 5 > 86, 7 > 87 & 10 > 86. That's all the "recipe" calls for when doing the conversion.

Please bear with me . . .
Klima socket #s followed by Klima designations

1 = 31 ground to battery
2 =GM+ testing post > idle speed control, Control Unit
3 = TD not used
4 = VL
5 = 15 > 12 pin connector > auxillary fan relay
6 = 87k to kickdown switch
7 = 87 to compressor's k1 which is the electromagnetic coupling
8 = no pin
9 = GK+ to compressor's l1 which is the RPM sensor
10 = KL to pressure switch, refrigerant compressor, OFF 2.0 bars/On 2.6 bars
11 = GK- to compressor on the RPM sensor side
12 = T to S25/5 Temperature switch 115 degrees C for compressor/emergency cutout


The 10 amp fuse is fine on the OVP.

I have that info
I meant :
What pins on the ICE CUBE relay are coil and what are Contact switch??
The coil pulls in the contactor , so we know we need the contactor on pins 5 and 7 to get power to the C Clutch.

So, I need to know which are coil/contactor on ice..not on klima

Not being certain what signifies the coil/contactor I am going to try to provide a readable schematic below:

86 87 87a
o---, o o
| [=/=]-->-------/
o---' o
85 30

The [=/=] appears to be the coil??? Pin numbers are above & below the "o" pins. Pins for 86 & 85 tie to the [=/=] using , & ' respectively.

After posting above, I noticed the spaces are not present between 86, 87 & 87a so you need to visualize them being spaced in accordance with the "o" pins.

If I am reading the schematic correctly, 86 & 85 are coil, 87 = ? while 87a & 30 are the switch.
Steve

I think you need a relay that will put the coil across pin 5 and 10.
That way , when the PB is operated it will give the coil ground and complete the circuit [ through the pressure sw and PB unit.]

So, when this happen , the coil will pull in the contacts , which are wired across pin 5 and 7. This will power the clutch.
So, you see that pin 5 is common for both coil B+ and clutch B+.
Whereas , pin 10 is B- for the coil and and 7 is the closing of the relay to feed power from 5 through 7 to clutch.
If you draw this on the schematic , you can see how it works . [ coil across pin 5 and 10, switch across pin 5 and 7]Then you just have to make sure the ice cube inside wireing is applicable to place the coil and contactor pin in the correct places .

Pin 1 is a ground and not needed in this circuit, as you want to catch ground through PB and pressure sw.

UI think there are 2 different type relays , depending on ground switcin g or power switching

Here is an example :


GERMAN AUTOMOTIVE
Junior Member Join Date: Mar 2000
Posts: 14

THE COMPRESSOR RELAY CAN BE BYPASSED AS FOLLOWS,USING RELAY # 001 542 02 19 MAKE YOUR OWN JUMPER WIRES. TERMINAL #1 ON KLIMA TO #85 ON ICE CUBE,#10 KLIMA TO #86 ICECUBE ,TERM. #5 KLIMA TO #30 ICECUBE,AND #7 KLIMA TO #87 ICECUBE. CLUTCH WILL ENGAGE AND DISENGAGE AT PUSHBUTTON ASSY'S COMMAND.M.F.

Arthur,
I re-ran the series of test at the Klima socket because I remembered the last test involved the speed sensor and I was uncertain of the result. According to the service manual testing the voltage (in AC not DC) at terminals 1 & 2 should give > 3.8 volts at about 750 RPM and should increase the voltage as the RPMs are increased. I just measured it again and confirmed what I had thought I found the first time. The voltage starts at or about battery voltage (hard to tell since I am in AC voltage mode) and stays that way through out the RPM range. Any idea how I can safely bypass the speed sensor?

The only way I know is with the ice cube relay.
The problem, as I have mentioned , is some PB units feed power to the klima and some ground the klima. [ at pin #10]
So which relay is used depends on the PB switching.
If pin 10 is a switched ground [which I think yours is, as you stated neg reading ] then the relay uses pin 10 for the ground side of the relay coil.
If the PB #10 terminal is a power feed from the PB , then the ground for the relay coil is grabbed at pin # 1.
So, 2 different systems that will require different relay internals

here is a link that MBDOC has post in regards to rpm bypass.
I am not fimiliar with that circuit have no info to check into it..

http://www.peachparts.com/shopforum/tech-help/66197-c-rpm-sensor-bypass.html?highlight=bypass+speed

Steve -

Have been too busy to respond of late, apologies for the delay.

I believe your ice cube bypass is improperly wired. Arthur has identified the correct solution in his text, but the instructions he has quoted from a previous post apply to a gasser; diesels, for some mysterious reason only understood in Stuttgart, operate differently. I have successfully built and used an ice-cube bypass for my '87 diesel, though it has been a few years.

In general, a gasoline 124 sends +12v to pin 10 of the Klima as the signal to operate the compressor. Your diesel grounds pin 10 of the Klima socket to signal operation of the compressor. Use your DVM to check voltage between pin 5 & 10 with the a/c switched off, then on. I expect you to see indeterminate voltage during the first test, and a solid 12v on the second.

If so, modify your ice cube bypass as follows: pins 85 & 86 (the relay coil) connect to pins 5 (+12v) & 10 (PBC ground signal) on the Klima socket. Not sure if it matters which Klima pins are connected to which relay pins. If it doesn't work, try swapping pins 85 & 86 on the relay - some relays are sensitive to the direction of current flow.

Pin 30 on the relay is also connected to pin 5 (+12v) on the Klima socket. Pin 87 on the relay is connected to pin 7 (compressor coil) on the Klima socket. Pin 87a on the relay is unused.

So if it is all working correctly, when you push the a/c button in the cabin, the PBC grounds pin 10 of the Klima socket. Since pin 85 of the relay is now grounded, and pin 86 is connected to 12v, the relay activates. This connects 12v at pin 30 of the relay to pin 87 of the relay, which then sends +12v to the compressor clutch. The compressor switches on, you get cold air and a smile on your face.

A couple of notes on the bypass circuit. You will of course lose the RPM comparison compressor cutout circuit. Whether this is a bug or a feature I will let you decide. Having had a compressor seize up while crossing the west Texas desert, I rather like it.

You will lose the high temp cutout circuit. The Klima relay shuts off the compressor when engine coolant reaches 115C degrees. Of course, you can monitor the coolant temp and take care of this manually. Shouldn't ever happen in a properly operating car.

You will lose the full throttle compressor cutout. So you stay cool while passing, but it takes longer to pass. You can always switch to E/C before accelerating around slower cars.

Finally, the transmission kickdown will be disabled. At higher speeds the car will no longer drop into 3rd gear when full throttle is applied. You'll notice the Klima relay is actually labeled "Klima+Kickdown."

I ran the ice cube bypass for a few months, but decided to replace it with a fresh Klima once things were sorted. I had multiple problems triggering the compressor cutout: excessive air gap on the compressor clutch (due to normal wear), plus grease and oil on the compressor clutch surfaces. These two problems caused enough slippage to trigger the cutout circuit on the Klima relay. After fixing these issues, I reinstalled the original Klima. The compressor no longer cutout, but would switch on & off in a rapid, random succession. I ordered a new Klima relay, and all has been well since. I think all that diagnosis and work was in the summer of 2000; not exactly sure.

Guess my point is this: Klima relays do go bad. They do more than just switch on the compressor, so I see the ice-cube bypass as a temporary/diagnostic fix.

My $.03 (long post...)

- JimY

quick edit: Here's a link to a site with ice cube schematic & explanation: http://www.teamrocs.com/technical/pages/relay_basics.htm

jcyuhn,
Did you check Arthur's photo sketch? If you were in my place would you think he didn't like my computer (keyboard special) drawing?

Kidding aside, thanks to both of you. I got as far as attempting to check the voltage actions of terminals 5 & 10 with my TWO meters. The first one is a meter I bought about thirty years ago when I owned/operated a service station. It relies on the battery for the primary + & - leads and provides a voltage + clip/probe and one for testing ohms. Being digital, I tried to use the negative cable on terminal 10 but the meter won't work that way. So I hooked it up to the battery as I normally would and individually tested 5 & 10 just to see if voltage was present. I was surprised to find 0.34 volts at 10 while battery voltage was at 5. Next I used my little muti meter knowing it would not allow for small voltage readings. However, it does work directly with two probes. I checked with 5 (+) and 10 (-) and got the desired results switching the PB Controls on and off of AC. I will need to redo my ice cube wires tomorrow since my old bulldog suddenly showed signs of distress. He has a bad heart and has had three conversions. Being my best pal his last days find me staying as near as possible (hated to travel to Manchester today). Sorry for the long explanation yet I wanted to let you know I really appreciate the help and also that I am moving as quickly as possible to follow the advice. By the way, ultimately I want to find the problem and go back to the Klima. I am not so concerned with the risk of undetected compressor failure since I am very accute to any changes in noise and other operational issues. Kickdown is nice and the extra power under full throttle likewise, however in the meantime AC would be better.

I need to find and read (I have the CDs, MB Climate manual, and Haynes) the procedures for checking the compressor clutch gap and acceptable cleaning methods. Typically I use electromotive cleaner for anything electrical but I am not certain if it is advisable on AC (never watched any of my mechanics working on AC when I had my station). I love doing this stuff and wish I had another eight weeks straight of vacation (just finishing my eight) to keep sorting. Okay, too long. Its been one of those days and Brier (bulldog) isn't up to eating so he certainly doesn't want to listen/read my ranting.

I'll keep you posted and thanks again.

Being a "dog person", I sure understand your priorities.

Checking clutch gap is easy - just use feeler guages such as for valve adjustment or spark plug gapping. The clutch air gap is supposed to be 0.50mm, plus or minus some small amount that I cannot remember.

There are lots of options for degreasing the clutch. Brake parts cleaner would be one. Think I used a citrus degreaser intended for bicycles, rinsing with water. It's not rocket science, you just need a method to get it down into the clutch gap.

- JimY

Back at it . . . or almost. I toasted my spare ice-cube so I have four on their way. Additionally, I found a Klima for $40 and that has been shipped. I do intend to eventually find all of the gremlins and use the Klima the way it was intended.

I also had another dilema while testing. I had two multi meters and now I have a third. My digital ran from the vehicle battery so when I had to use one Klima socket for ground and another positive I had to switch to my little needle meter. It wasn't designed for automotive use and the voltage scale imposes real limits (10 volts, 100 volts, etc.). So today I went to Sears and purchased a relatively inexpensive digital that gives me more meter than I need. Actually, since it has the temp probe I can monitor my ACC temps from the vents once I get the ACC operational again.

While I'm waiting for delivery of my relays, I want to keep testing. An area I am uncertain of (there are still many of those) is the air gap on the compressor's clutch. First, if by jumping 5 & 7 at the Klima socket engages the compressor is it safe to assume that the air gap is approximately correct? If I do need to check it, is there a nut to remove at the front (after loosening the belt) that will provide access to the clutch components?

I'll keep you posted.

P.S. Brier, my bulldog seems to be doing better. He is snoring up a storm at my feet as I type. I think the brief ride in the MB yesterday did his spirits some good. He still prefers the '77 VW 7-passenger bus since he can stretch out and snore. Just over eight years old and with a life expectancy (according to the breed) of 8-10 he is probably doing as well as I can expect. What big babies these four-legged family members can be.

Steve -

Didn't you post the air gap question in a separate thread? I think I answered there. Either that or I'm hallucinating again. Wouldn't be the first time.

Anywho, long and short is no, jumping the Klima and having the compressor engage is no guarantee it'll work with a good Klima in place. Mine worked fine with an ice cube relay, but would cutout with a Klima. Check the air gap and I bet you'll find it to be 0.8-0.9mm. That's flaky territory - the compressor is capable of working OK, but there's enough clutch slip to trigger the Klima speed comparator circuit.

Setting the air gap is pretty easy. Remove the 10mm nut which retains the front plate of the compressor. You need a special puller to remove the plate. It's nothing fancy, most McParts stores will rent/lend you one - I bought mine for ~$20. Space may be tight between the clutch plate and the radiator. With the clutch plate removed, you'll find one, or two, or maybe three small washers on the compressor shaft. These are spacers. Try removing one or two of them to see which result gets you closest to 0.50mm. Don't go below 0.35mm - that's minimum spec. If you wan to be really obsessive about it, your local auto a/c place will sell a kit with a variety a spacer rings so you can set it just right.

Assuming you can get the clutch plate off the front of the compressor without pulling the radiator :) it's a 15 minute job.

Good luck,

- JimY

Jim,
You are probably not hallucinating . . . its just I was lost from before starting since I did not know where & how to set the air gap. That being said, thank you for the instructions because I will have NO problem following them. Though I own a number of pullers, I will check to see if they have one at the local parts shops for AC pulleys. I noticed the lack of room when I changed to the newer type vacuum pump w/o having to remove the fan & front portion of the shroud. Being the careful type and having reasonably good right/left dexterity, I should be able to accomplish it w/o damaging the radiator.

I'll keep you two posted and also be anxious to try my new temperature probe on the cold air that will be coming through the vents.

P.S. Tried my new digital multi meter on the Klima socket tonight with terminals 5 & 10. It worked like a charm giving me < 1 volt in digital. Should have updated my equipment long ago. The audible feature was a help since I didn't have to take my eyes from the probe placement as I went all over the place checking resistance (olde boys with new play toys).

My two sons (24 & 25) and their friends have really started to take an interest in my '87 300TD. They wanted to borrow it for their Friday night trip to Epping, NH drag raceway. They all drive the new vehicles yet wanted to take my diesel wagon . . .

I am attempting to pull the compressor clutch in order to check the air gap. How in heck do I hold it from turning so that I can loosen the 12mm nut? :confused:

You know, I can't remember what I did to hold the clutch plate from turning. I don't think the 12mm was all that tight when I worked on the compressor. How about a strap wrench, like for a spin-on oil filter?

BTW, here's a link to a site which explains rebuilding a nippondenso compressor. Most of it isn't relevant, but some of the photos & steps might apply to your task. http://www.pelicanparts.com/techarticles/911_Nippondenso_rebuild/911_Nippondenso_rebuild.htm

Best of luck,

- JimY

Just received my shipment of ice-cube relays and what was supposed to be a new Klima. The latter was a fuel pump relay so the Klima is now being shipped tomorrow.

So, I took the next step and wired the ice-cube the correct (thanks) way. As you guys already knew, it worked. YES!!! :D Cold air again!!!

Thanks for the suggestion of the strap wrench for holding the compressor clutch plate (not certain if that is the actual name). One of my boys heard me say something like, "what a dumb sh_t I am" and asked what was up. I told him what you suggested and he agreed with my self assessment. He took it one step more by reminding me that I usually do a better job thinking of things than McGuiver. Guess the frustration was taking its toll.

I am hoping that I'll have access enough to check the air gap since I am not equipped to remove the compressor.

With patience I'll be able to get the Klima back in and working as it was designed. Keep you posted.

PS Don't know if either of you happened to see my stringtrimmer line lodged in the sunroof post or not. While using the line to clean my rear drain tubes I got the line lodged tighter than tight in the rails of the sunroof. That was a couple weeks ago. I tackled removing the sunroof lining for the first time this morning and was eventually able to free the line. Now I just need to read how to adjust the micro and/or clutch stops. I tried for awhile with the white knob near the motor and that seems to be the way to do it (used a 3mm wire in the hole). Not quite correct yet but closer.

Thanks again guys. The cold air seems great.

After cleaning up my ice-cube relay wiring job (shortened the wires and made a decent under-hood fit) I spent time driving my '87 300TD with AC on to see what type of readings I would get at the vents. Using my digital multi meter with temp probe, I got a sustainable low temp of about 47-48 degrees at the center vents. Ambient temps during my trials ranged from just over 80 to mid 70s (most of the time). With AC on the engine temp was primarily just over 80. Idle, of course, resulted in the vent temps to climb but no more than I would expect. Though I am going to eventually complete the task of finding (expecting the compressor clutch gap) the problem, solving it and getting a Klima back in, I am thrilled with the help/results. I'll keep you posted.

I've got similar problems with the Klima on the SDL. I traced it down to the compressor speed sensor. The sensor should provide a reading of .3V at idle. It provides less than .2V. It should have a resistance of 550 to 650 ohms. It has 1000 ohms.

It appears that this speed sensor is on the back of the compressor on the shaft centerline.

There is some mention made of an air gap. But, I'm thinking that it's not applicable to this unit?

Can anyone, maybe Arthur, comment on how the speed sensor would be setup on this compressor and how to remove it??


Edited:

After making up the bypass ice cube relay and installing it, the problem is identical:

The compressor runs for about four minutes and shuts down. No change in symptoms. :mad:

So, the low pressure switch is ruled out, the Klima is ruled out. What else can possibly shut the compressor down and leave it shut down?

I started another thread on it. I'm at a loss.

http://www.peachparts.com/shopforum/tech-help/130636-300-sdl-c-electronic-controls.html

Brain,

I had a similar problem. Compressor sensor resistance was not correct. Replaced the 3 wire connector on the compressor, AC works fine!

Yes, I thought that was the case with this one, as well. But, removing the Klima from the system and running it with the ice cube relay confirmed the problem remained. So, the sensor on the compressor was doing the proper job.

If you bridge pins 5 & 7 on the Compressor Relay Socket, does the compressor continue to run?

Yes, it did.

Looks like you have already ran the 6-7 tests for the Compressor Clutch Relay.

You may want to run the AC Control Unit Diagnostics. alldatadiy lists all the tests.

The compressor engagement on my car was intermitent. Then it would engage at startup but disengage shortly. Bridging pins 5 & 7, the compressor stayed engaged. Repalced the Compressor relay. Did not fix the problem. Took it to the MB dealer, that is another story! I have yet to find a satisfactory MB dealer. End result, I was overcharged and problem not fixed. I declined the $675 speed sensor repair. For that price, one can get a new compressor!

Ran my own checks, all 6 of them for the compressor relay. Ordered the ICe Cube Relay from ebay. Meanwhile, found power connector at compressor loose. Replaced connector, around $5. Everything working fine. Temperature at the vent 38F.

Bridging pins 5 and 7 eliminate the Klima and the PBU from the system. So, you really don't know anything, at that point, other than the compressor clutch works properly. The problem can then be any of the signals to the Klima, the Klima itself, the PBU, or any of the signals to the PBU.

In my case, using pin #10, the ground from the PBU, the problem remained. So, this now effectively rules out the Klima and all inputs to the Klima.

A second PBU eliminated the problem, however, it's more likely that the evap temp sensor is out of limits (2.2K resistance) and causing a default in one of the PBU's. They are not exactly identical........one of them is a newer version and must have slightly different internal circuitry.

I hear you regarding the dealers. You take the vehicle there thinking that they have better knowledge and troubleshooting skills than you do. In reality, you get a parts changer with his head up his ass.