CaliBenzDriver

Now switching to tedious discovery mode...
It's a different logic than trying to match known issues to conditions.
This is discovering what is causing this unknown [to me] issue.

If you have knowledge about this please through us a bone.
I know the OCP Module is known for similar issues even without the occasional rain oxidation when its dead.

WHAT IS IT WITH OCP...
Fixing these beautiful vehicles is an unnecessary waste use of time.

Here is what I found.... There are NO faults despite plenty of deep issues that should be flagged as bad. Keep this inind as it relates to interesting when troubleshooting the HVAC!

My OCP "Cabin Temp' Sensor is a totally random number unrelated to current temp.

Now my other OCP Data PID's are also going bad...


Menu of available OCP Data PID's ...


OCP showing missing Sensor TEMP & Fan Status


Missing Battery voltage data by OCP !!


The AAC HVAC Module simply makes up missing numbers (no fault)

The funny thing is OCP works "perfectly"!
It appears not to be missing voltage supply.


> WHERE I am going is :
1-- a new Shielded DATA line to extremities. . . (Trunk lid, R-SAM, you mame it...)

2-- a Xentry factory reset to relearn Data scale with current clean GND level.

3-- Revisit vitals: Power/GND, CAN/LIN... (Spare replacement OCP tried &#128578.


> SURYA'S NETWORK MAP:
Can you please with your itchy hands... the network diagram showing ALL vehicle connected modules.
I want to chart the network speed & lenght then upgrade long runs with shielded cable... super fast dara, no more delays - you no me, I am a latency killer for life.

This is going to transform some of these cars, thanks to MBWorld for MB GUYS 👏

We need to school ourselves in network distribution cabling vs. speed & distance. A few CAN strings need a bump from ridiculous grandma twisted pairs. Ain't no good!


> WHAT IS THIS:
I bet that I am going to fix some issues by upgrading THE CURRENT UNDERSIZED CAN-BUS TWISTED PAIR CABLE TO THIS... cheap but up to speed!

-----------------
I just got done dealing with this exact problem with my beautiful all wired alarm panel. Dual power supplies extension.
The unknown issue was my device BUS runs were using twisted pairs.... ****!

I've worked the past 4 days at rewiring my alarm power distribution before vacation.
Now 5 separate runs where used to one only. Ican remote control power shading during emergency power outage (Can discuss if your interested in alm pnl).

The DATA LINE from Internet module to PANEL was twisted pair... I've just bumped it to SHIELDED 👍

A REMOTE EXPANDER with two keyboards were on a ridiculous 70Ft twisted pairs terminated through alligator clips ... the system was so stable, I was afraid of destabilizing the reliability I had built.
Since I rewired my new "lean power" upgrade, I dealt with data, thank God for not doing a cheap job with power only.
The Data speed upgrade through that shielded cable is amazing. When you know a system well, you can tell how it's working.
-----------------

> MB NETWORK CHAOS:

• Horn sounds after unlock the doors !!
• Sloppy transmision shifts !!
• RFK crazy com faults !!
• Headlights cooling fan when cold
• Any known R-SAM don't sleep ??
• ... your favorite bug here...

.


Building electrical shielded... nothing too fancy!


Here goes SHIELDED @ 22AWG... ⚡

Imagine what that's gonna do to all electrical noises pumping chaos into differential voltages noise-hardened CAN bus... I am pretty motivated to test that against "Slow transfers".


> Patch CAN upgrade cable:
Twisted pair cable is a low bandwidth network conduite for bus data.
Glitches and ringing impedance is what we are dealing with. Once you know, you shield!
CAN-B line from OCP around windshield to where: F-SAM ??
CAN busbar lines to R-SAM / F-SAM /Bumper modules


> SPLIT these 2 topics apart:

• OCP Module ghost Data
• SHIELDED Cable CAN upgrade

or one and the same??

I think we have secured a cruiseship WIFI package so I can still connect to learn what makes "happy CAN".

Already i can see "Error Counts" are on the menu... modules indeed know when they are stuck in the mud -

It would only take a second to collect all green lights from modules. NOPE! Couple smart PhD software Mgrs decided their system could suck and you could try to drive as-is: that's us every day! Point being when errors pile up... MB don't want to be legally aware and not do anything. Modules buggy wiring harness is recognized through measured error rate (honest German design) but ignored by MB application layer.

Is there anyway in Xentry to diagnose module error rates ?? This would be helpful in picking modules with bad COM modules.... we are going to guess that trouble-list based on traffic, speed, distance.

The CAN differential networking is nearly great at fault-tolerance (dismal speeds) but some VIP Module REQUIRE bandwidth throughput.
Ex: Imagine connecting an entire city through ONE SINGLE dial-up 56kbps line. No problem..." it's fault toletant"... but the bandwidth requirement is too huge to prioritize over 56k traffic speed.

Let's see what the hands-on results show

✈️ 🛳️

S-Prihadi

Cali,
Find attached CAN BUS wiring, let me know what I missed.

S-Prihadi

Now, yours is N70, so your OCP uses CAN BUS and not LIN like mine.

01. Make your own CAN-BUS map, from the wiring diagram. Do not rely on the provided topo by MB, that one is simplified version for data flow and does not show physical cable routing.


02. I can not yet define with any certainty, if a CAN wire goes wire into Front SAM N10/1 , is that for Front SAM CPU or for Gateway N93 which is inside Front SAM.

Above is my own MAP of the CAN-B, I list this down one by one from wiring diagram. It does not show the LINs, as LINs for some reason is not listed in CAN BUS 101 documents.

Now for X30/32 distributor, notice there are 2 connection to N10/1. Slot 1 and Slot 5.
I then assumed Slot 1 is for N93 CPU and not Front SAM CPU.
I then assumed Slot 5 is for Front SAM CPU, and not gateway N93.
Do remember, there is no scanner, not even Xentry which will show N93 , it will show N10/1 Front SAM only.
Do not get confused with a stand alone N93/7 which is not N93 the MAIN GATEWAY. N93/7 is the Chassis Gateway Control unit for cars with Code 23P option.
I guess N93 designation is always a GateWay, but which gateway is the question.

From the document I named FRONT SAM AS CGW







Now, Xentry topo does not recognize N10/1 Front SAM, it uses N93 . My car below.

But in diagnosis page where all modules are listed, there is no N93, only Front SAM N10/1 is mentioned.... LOL

S-Prihadi

When you done mapping your CAN B linked modules like how I did using the Excel , we can start troubleshooting together.
-58F is -50C , I think that is like a open circuit value.
Some values on modules are substituted value, when and if module thinks the sensor is not there.
Its like a simple fail safe, but usually DTC will appear after a while, usually.

May I suggest you get the baby Launch Creader Elite for Benz like the one I have, it may read more data and DTC than you current baby scanner.

S-Prihadi

UPDATE :
So now car has done a few hundred kilometers since the recharge of virgin R134A.
The refrigerant has gone round and round enough to pick up any "dirt" in the HVAC system.


I inspected the refrigerant today.
Very nice and clear, although my oil is yellowing and there is nothing I can do..... yet.









Compressor oil




I found a way to replace my compressor oil partially, without dismantling anything.
I have verified with Master Tom Lech ( my mentor )..... : will my method work or not ? He said YES, it is do-able with 1-2 gram accuracy scale.

This is the plan :
I have bought filter drier of 3 sizes.
Emerson EK-52 of 5 cubic inches ( 81 cc ) or , EK-163 16 cubic inches (262 cc ) and EK-304 of 30 cubic inches (491 cc ). I believe the cubic inches is the internal volume of the unit.
This is for home or industrial HVAC system, hence it is cheap unlike MB selling the filter drier at US$231 and special order 2 months.
EK series contains desiccant for water vapor and acid capture. Acid formation is what happens to oil with water moisture and is the compressor killer.
It is the nature of these filter drier , it will be saturated with oil too.....like how oil will wet the MB filter drier.

So I will get 3 side benefits.
01. Existing moisture removal, so my system will be drier than before both the R134A and the compressor oil.
02. Acid removal from oil.
03. 20 micron filtration, if there is any debris whatsoever.

Emerson EK series white paper : https://www.copeland.com/documents/e...en-4858120.pdf

As to how much oil will actually be wetting the internal of the filter drier, I do not know yet.
I will weight the filter drier new and used and work out the actual oil trapped inside it, and will re-inject new oil of the same amount.
MB WIS specified if we replace the filter drier in our W212, 20 cc of oil is what we need to put back into the HVAC system.

If by using small or medium size Emerson EK series filter drier I have, and if I can get oil trapped between 15 to 50 cc I would be very happy already.
My HVAC system is only a 120cc total oil capacity.
If I do a total 240cc of oil exchange, perhaps I would be able to get the 120cc oil capacity I need to be 75% of it being new oil.
Based on color of oil or R134A oil mix, I would be able to see how much super clear new oil has replaced the yellowing old oil.


With the MasterCool Inspection Sight Glass and the Emerson EK series drier ahead/upstream of it, I can create 2nd refrigerant flow path and "catch" the oil while cleaning and drying my HVAC refrigerant and removal of acid in compressor oil.
This will take time and patience, but sure is better than complete HVAC system removal purely for cleaning or oil replacement.
The only thingy I can not do with my method is, cleaning oil film at evaporator and condenser internal micro channel. These internals do have oil coating on them and
too much oil coating will reduce heat exchange efficiency.

Here is a good video on how compressor oil can be over wetting or stuck at the evaporator when refrigerant charge too low and the compressor will be oil starved.

Start at 6:30 LOW CHARGE - Oil Drop Out


=============

While engine and HAVC is running, if one blast out refrigerant out of the HP port fast and careless, lots of compressor oil will spray out from HP port.
This is the method I will use to "fish-out" the compressor oil.