Mercedes W220 Climate Control
Read Out Fault Memory And Erase Fault Codes
Turn the key to the on position.
Turn the a/c switch on.
Both AUTO buttons should be pressed out.
Push and hold both the charcoal filter button and REST button at the same
time and release. You should now be in diagnostic mode.
Scroll through the faults using the left temperature selector.
To delete the faults press in the left AUTO button and then press in the
right AUTO button then press out the right AUTO button and then press out
the left AUTO button. The display should show “deleting fault codes”.
Thanks for the input - still having problems but greatly narrowed nown as result of your help.
Tried to add 134a this am, wouldn't take any.
leaning toward the evap temp sensor, as Item #50 on diagnosis indicates that the Comp unit is off -recei8ving no power.
I located the speciific diagnositc proceedure for the 1997-1999 C280
Thought some of you may be able to use it. as the read-outs are clearly identified as well as fault codes.
A/C SELF DIAGNOSTIC SYSTEMS - 1990-97
Baum Tools Unlimited Inc. 941-927-1414 / Technical Support 800-804-1002 or tech@baumtools.com 93
202 Chassis from 9/95
READING ACTUAL VALUES
1. IGNITION : Position 1
2. Set temperature selector to 72 degrees F.
3. Press the REST button for more than 6 seconds.
4. The left display will alternately show the number "01" and the in-car temperature.
5. Press the FAN button and the next component number and its value will be displayed.
6. Press the REST button to end the test program.
COMPONENT UNDER TEST
Number Component
01 In-Car Temperature Sensor with Aspirator Blower (B10/4)
02 Outside Temperature Sensor (B14)
03 Heater Core Temperature Sensor (B10/1)
05 Evaporator Temperature Sensor (B10/6)
06 Engine Coolant Temperature Sensor (ECT) (B11/4)
07 Refrigerant Pressure in Bar
08 Refrigerant Temperature Sensor (B12/1)
09 Not Used
10 Blower Control Voltage
20 Control Current for Auxiliary Fan exp. : 7 = 7 mA
21 Engine RPM. example 00..99 (x100) = 9900
22 Vehicle Speed
23 PIN 58D exp. 99.0 = 99% of Battery Voltage
24 Battery Voltage : 12.8 = 12,8 Volt
40 A/C Controller Software Version Coding
41 A/C Controller Hardware Version
42 Variant code 1
43 Variant code 2
50 Not Used
51 Not Used
52 Not Used
54 ON/OFF A/C Compressor emergency off signal from engine control module.
202 Chassis from 9/95
FAULT DIAGNOSIS
1. IGNITION : Position 1
2. Temperature selector wheel : "LO"
3. Within 20 seconds press the REST and DEFROST buttons simultaneously for more than 5 seconds.
4. The LED in the RECIRCULATE button flashes and "dI A" appears on the display.
5. Press the AUTO button until all DTC's are displayed and recorded.
6. The current faults are displayed first, then the intermittent faults. "END'" is displayed when all codes have been displayed.
7. To erase codes press v and ^ simultaneously for more than 5 seconds. The display will then show "---". Press AUTO to cancel
the erase.
8. IGNITION : OFF to end the test program.
FAULT CODES - 202 Chassis from 9/95
DTC Readout Description
026 CAN Bus Communication
226 In-Car Air Temperature Sensor (B10/4)
227 Outside Air Temperature Sensor (B14)
228 Heater Core Temperature Sensor (B10/1)
230 Evaporator Temperature Sensor (B10/6)
231 Engine Coolant Temperature Sensor (B11/4)
232 Refrigerant Pressure Sensor (B12)
233 Refrigerant Temperature Sensor (B12/1)
241 Refrigerant Level
416 Coolant Circulation Pump (A31m1)
417 Left Duovalve (Water Valve) (Y21y1)
418 Right Duovalve (Water Valve) (Y21y2)
419 A/C Compressor Electromagnetic Clutch (A9k1)
420 Closed (Idle) Throttle Speed Increase
421 Pulse Module (N65)
422 Serial Interface Connection (K1) to Instrument Cluster (IC)
451 Diverter Flap (Y11/3)
452 Blend Air Flap (Y11/3)
453 Fresh/Recirculated Air Flap (Y11/3) Long Stroke
454 Fresh/Recirculated Air Flap (Y11/3) Short Stroke
455 Defroster Outlet Flap (Y11/3) Long Stroke
456 Defroster Outlet Flap (Y11/3) Short Stroke
457 Footwell Flap (Y11/3) Long Stroke
458 Footwell Flap (Y11/3) Short Stroke
459 Serial Interface Connection (K2) to Instrument Cluster (IC)
462 Wide Open Throttle (WOT) Position Signal - Diesel Engine Only
Will update as I progress. I may take it to the big city and have a professional AC Shop evac and recharge.
I'm in a very small town and don't trust the Good Ole Boys working on such a fine German Machine.
Thanks again,
Bob
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