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Q: climate control not operating on 1998 Mercedes-Benz CLK320

Hi, the climate control panel seems jammed on certain commands: EC is on and won't turn off (economy); Auto is on and won't turn off; other commands not operable. The system is filled with freon and no leaks found. Can the panel be re-set or re-booted?? Thank you, Martin
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Sharing the knowledge:

Sensor Data.
First we’ll get the values of all the various climate control sensors. These sensors constantly monitor data like air temperature, refrigerant pressure, etc. Odds are if something’s wrong, a sensor will pick it up. Let’s get started!
• Start your car.
• Press the “AUTO” button on your climate control.
• Turn on the A/C (i.e. “EC” light must be off; if the light won’t shut off, continue with this test. We’ll address your “EC” light on the next page.)
• Let the car idle for about 3 minutes.
• Set the temperature on each side to 72°F. You can do this quickly by pressing both the red and blue arrows simultaneously.
• Press and hold the “REST” button for five seconds or until the left side of the display says “01.” The left side indicates which sensor you’re checking. In this case, #1 is the in-car temperature sensor. The right side of the display shows the value of sensor #1 (in this case, the actual in-car temperature).
• Press the “AUTO” button on the left side to move to the next sensor. Press the “AUTO” button on the right side to move to the previous sensor.
• Record the ID number of each sensor (left side of display) and its corresponding value (right side of display). For example, in the picture on the right, you would record that sensor #5 has a value of 6.
o You only need to do this for sensors #1-8. You can write down the values for the other sensors, but they’re not really related to air conditioning function.
When you are done, press the “REST” button again to exit the self-check mode.

Sensor codes.
01 In-car temperature sensor.
02 Outside temperature sensor.
03 Heater core temp, left.
04 Heater core temp, right.
05 Evaporator temperature sensor.
06 Engine coolant temperature.
07 Regrigerant pressure in bar (e.g. '4' is 4 bar).
08 Refrigerant temperature.
09 Not used.
10 Heater blower control voltage (normal 08-6.0, meaning .8 to 6 volts).
11 Emissions sensor voltage (to detect atmospheric gases and recirculate interior air).
12 Sun sensor voltage (to shift airflow in car).
20 Control current for auxilliary fan (electric fan on radiator, given in milliamps or mA).
21 Engine speed (x100).
22 Road speed (km/h or mph depending on installation).
23 Battery voltage at terminal 58d (as a percentage of total voltage, e.g. 99.0 = 99%).
24 Battery voltage (e.g. 12.8 = 12.8V).
40 Climate control software version.
41 Climate control hardware version

Malfunction codes.
Now that we have all the sensor values, let’s check the computer for malfunction codes. Read this carefully, because you have a 20 second window after switching on the ignition to load the trouble code display mode.
• Ignition must be switched on. 20 second timer starts.
• Increase the left side temperature (left red arrow) until left side says “HI.”
• Decrease the right side temperature (right cold arrow) until right side says “LO.”
• If your 20 seconds passed, switch off the ignition and switch it back on. Your HI/LO settings will be preset. Timer restarts.
• Press and hold the “EC” and “REST” buttons simultaneously for at least five seconds.
• The screen will go blank.
• Load the first code by pressing the right side “AUTO” button.
• If you have any error codes in memory, the screen should look like the figure on the right. The ‘E’ stands for “error.” In this case, we have error code B1234.
• Write down each error code. To cycle through the codes, press the right side “AUTO” button.
• When you finish, press the “REST” button to exit.

Deleting the fault codes.
Service Procedure:
1. Read and clear DTCs in the A/C control module using a push-button on-board procedure. Turn the key to the ignition “ON” position.
2. Set the left temperature selector on “HI” and the right temperature selector on “LO.”
3. Within 10 seconds, press and hold the “REST” and “EC” buttons simultaneously for six seconds, then release.
4. The Light Emitting Diode (LED) in the recirculation button should begin to blink. The display should read “di A.”
5. Press the right “Auto” button to display DTCs. Keep scrolling through the list by pressing the right “Auto” button until the display shows “E FF.”
6. To erase DTCs, press and hold both “Auto” buttons simultaneously for three seconds and release. The display should show “D FF.” Switch off the ignition.
7. Restart the engine. If the “EC” button lamp is illuminated, press and release the “EC” button. The lamp should go out. If not, recheck for DTCs Key On Engine Off (KOEO), then recheck compressor operation.

The following are where I found the fault codes listed relating to the Air Con.

B1000 HRA Headlamp range adjustment: Supply voltage of the control unit is too low (undervoltage)
B1004 LCP Lower Control Panel: Control unit does not match vehicle type
B1056 Automatic Air Conditioning: Problem in CAN communication with control unit DCM-RL
B1201 Electric seat adjustment front left: Hall sensor front height
B1213 If seat memory installed: ext left rearview mirror voltage faulty
B1214 If seat memory installed: ext right rearview mirror voltage faulty
B1226 In-car temperature sensor (B10/4)
B1227 Outside temperature indicator temp sensor (014)
B1128 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
B1246 PTS Parktronic: A42b1 (left outer sensor, front bumper) The plug connection has poor contact or is loose, or the sensor or cable is faulty
B1310 Left/Window airbag sensor is defective
B1315 Problem in Front passenger child seat recognition
B1416 Coolant circulation pump (M13)
B1417 Duovalve (Y21y1), left
B1418 Duovalve (Y21y2), right
B1419 Electromagnetic clutch (A9k1)
B1420 Idle speed increase
B1421 Pulse module (N05)
B1422 Series interface (K1) connection to instrument cluster (A1)
B1423 Switchover valve block (Y11)
B1424 Activated charcoal filler actuator (A32m2) open
B1425 Activated charcoal filler 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
B1476 Airbag malfunction indicator and warning lamp is defective
B1481 HRA: Part E2m1 (Right headlamp range adjustment motor) has short to ground
B1489 HRA: Part E2m1 (Right headlamp range adjustment motor) has open or short to positive
B1492 HRA: Part E1m1 (Left headlamp range adjustement motor) has
short to positive
B1617 Part E19/1 (Left license plate lamp) is defective
B1618 Part E19/2 (Right license plate lamp) is defective
B1628 Part E2e5 (Turn signal lamp) in module E2 (Right front headlamp unit) is defective.
B1703 Intermittant No Start in AAM Immobiliser Module
B1729 PSE Pneumatic system doorlock Control Module A37
B1736 Navigation system's CD Player: Check General CD, Check CD data block, Flimsy CD data
B1768 Faulty open data flap limit switch (0025) Front flap
B1773 HRA: Zero position programming has not yet been carried out or is not possible
B1850 Electric seat adjustment front right: CAN communication interrupted with DCM
le Security Control Module
The conditions you are explaining indicate a fault in your a/c system. I recommend having the vehicle looked at by a professional that is capable of scanning every vehicle system.
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