http://www.benzworld.org/forums/w210-e-class/1384396-automatic-climate-control-diagnostic-trouble-code.html

Automatic Climate Control Diagnostic Trouble Code (DTC) Memory
	Preparations for DTC readout:

Ignition ON
Temperature selector left "HI", right "LO".
Within 20 seconds, press REST and EC simultaneously for more than 5 seconds
The led in the RECIRCULATE button flashes and the display shows "di R"
Press AUTO repeatedly until all DTC's (refer to DTC table) are displayed. Record each DTC as it is displayed.
Each malfunction (short circuit, open circuit, etc.) has a specific DTC assigned to it.
The letter "E" (Error) is displayed in the left side of the display and the DTC is displayed in the right side of the display. By pressing the right AUTO button, the next DTC stored in memory will be displayed.

To erase: Only possible after all DTC's are read out. Simultaneously press both AUTO > 2 secs. "d" will be displayed in the left side of the display window and "FF" on the right side.
To cancel erase: By pressing AUTO the current faults will appear again.

Set temperature selector to normal setting.
Turn ignition OFF to end test.

DCT table:

B1226 - In-car temperature sensor (B10/4)
B1227 - Outside temperature indicator temperature sensor (B14)
B1228 - Heater core temperature (B10/1)
B1229 - Heater core temperature (B10/1)
B1230 - Evaporator temperature sensor (B10/6)
B1231 - ECT sensor (B11/4)
B1232 - Refrigerant pressure sensor (B12)
B1233 - Refrigerant temperature sensor (B12/1)
B1234 - Sun sensor (B32)
B1235 - Emissions sensor (B31)
B1241 - Refrigerant fill
B1416 - Coolant circulation pump (M13)
B1417 - Duovalve (Y21y1), left
B1418 - Duovalve (Y21y2), right
B1419 - Electromagnetic clutch (A9k1)
B1420 - Idle speed increase
B1421 - Pulse module (N65)
B1422 - Series interface (K1) connection to instrument cluster (A1)
B1423 - Switchover valve block (Y11)
B1424 - Activated charcoal filter actuator (A32m2) open
B1425 - Activated charcoal filter actuator (A32m2) closed
B1432 - Non-USA DTC
B1459 - Series interface (K2) connection to instrument cluster (A1)
B1462 - Wide open throttle (WOT) position signal: diesel engines 

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http://www.benzworld.org/forums/w210-e-class/1166514-climate-control-diagnostic-tool.html

RE: Climate control as a diagnostic tool
01 = In-car temp sensor
02 = outside temp sensor
03 = left heat exchanger (heater core) temp sensor
04 = right heat exchanger sensor
05 = evaporator sensor
06 = coolant temp
07 = refrig. pressure in bar
08 = refrig temp sensor (23*9 = 23.9deg C)
09 = nothing
10 = Blower control voltage (great for evaluating blower controller problems)
11 = emissions sensor (B31) e.g. 3.1 = 31.v
12 = sun sensor 4.2 = 4.2v
20 = aux fan control 6.1 = 6.1ma (max 10ma)
21 = engine speed
22 = vehicle speed
23 = Circuit 58d e.g. 99 = 99% of battery voltage
24 = BATTERY VOLTAGE e.g. 12.5 = 12.5v
30 = left rear air conditioning heat exchanger temp sensor (not all vehicles; obviously)
31 = right side
32 = rear evap temp sensor
33 = blower control voltage rear 0.8(MIN) - 6.0(MAX)
34 = left rear temp selector
35 = right side
38 = software status e.g. 37 rear air conditioning
38 = hardware status e.g. 37 , rear air conditioning
40 = control module version software status (?)
41 = control module version menu hardware status
42 = control module variant code 1st number
43 = variant code second number.

You have a compressor problem if your climate control will not come out of Econ mode. Have your system recharged.