The whole history is on the thread:

c280 1997 Climate Control - classic cold + hot blow

Right now I am only separating a specific help request on how to define the right version code to the CCU

Run all the diagnostics (from the climate control unit)

1. CCU seems to be Ok and sensors are issuing correct data
2. Big finding: Version Coding was not Ok. I recoded it (based on my understanding of the instructions) and the system is performing almost OK.
3. I found an intermittent diag code pointing to the auxiliary water pump.
So, probably Richard was right all the time (full thread for details) . (and I have two issues: version code AND aux water pump) This is true IF I did the right Version Coding.

So I am back asking for support - now on version coding.

Let me show what I did (based on Alldata and StartekInfo)

Car is a 1997 C280 L6 w/ push button CCU (buttons around LCD window) (Chassis 2020281F493373)

Values to be selected _________ to be used if

COD - new unit - no programming so far
00 - Serial interface (K1) (this relates to the connection to the instrument cluster)
02 - K1+K2 (as of MY 1997) (K2 also relates to connection to the instrument cluster)
08 - refrigerant fill level check switched off (up to MY 1997)
10 - serial interface K1 + K2, refr. fill level switched off (as of MY 1997)
18 - with engine/climate control electric cooling fan
32 - aux cooling fan not available (as of MY 1997)

I decided for 10 and coded the CCU this way.

Reasons:
a. Newer models seem to be K1+K2 (sure???)
b. It is said that 1997s have fill level check off (my interpretation of the table above)
c. 10 is the combination of a and b
d. There is NO engine/climate control electric cooling fan (the car has the radiator propeller+ clutch) and the two auxiliary electric fans) (I say that based on visual inspection of the car)

So, from all I said I am not totally sure about the K1 and K2 thing. All my searches did not suceed...
Any help is VERY welcome.
Jorge


PS1: My CCU is A 202 830 1485 (as per EPC)
PS2: same source: instrument cluster is A 202 540 6697

Codes 2 OR 10 should work.

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M.B. Doc,
Many thanks for your support.
So, I will leave it as 10 and follow on testing the system.
Should the auxiliary w. pump intermittent error code come back I will test it with 2.
If the problema persists I will declare my pump as marginally good and decide if I simply live with it or try some brush cleaning or even replacement.
So far the AC is 99% Ok. This is a huge progress over the pre-coding, when the CCU itself was considered defective.
Best regards, Jorge
PS: MB ACs are very complex as compared to the vanilla AC solutions.