503C43 ////AMG

So I am aware that when you hold down the rest button it brings up the DTC but I was messing around with my climate control unit and I held down the recirculation button. It brought up "00" and when I pushed the + or - button it would make the "00" go up or down. I kept doing it all the way up to "30" but I haven't noticed that it did anything. Does any one know what these numbers mean?

503C43 ////AMG

hmmmmm....... 140+ views and no one has an answer

MarcusF

I know some of the AC diagnostic codes, but I've never seen a 30.

503C43 ////AMG

Yeah weird..... the numbers would go up in increments of 2, I stopped at 30. I assume they would of kept going. I am thinking this was different than the DTC. I didn't hold down the "rest" button I used the recirculation button to get to this. I am now concerned, If Marcus doesn't have an answer I am not sure who will.

503C43 ////AMG

Ok once again the white lab coat had to come out and I was transformed into the MB tech extraordinaire..... after messing around in my car and watching everything I figured it out. What I have stumbled across is how to control the level of back lighting on your climate control unit. Here is how to do it:

1.) I had my car off when I did this, not sure if you can do this with the car on

2.) Press and hold the recirculation button (large button on the right hand side of the climate control unit) for a couple seconds, DO NOT LET GO AT ANYTIME

3.) a 2 digit number should pop up, for me it was "00" ("00" is the dimmest)

4.) Keep holding the recirculation button and use the + and - buttons to get the desired back lighting level (+ makes it brighter and - makes it dimmer, "00" is the dimmest and "50" is the brightest

5.) Let go of the recirculation button and the numbers will disappear but the back lighting level will stay at the level you set it at

I searched and searched the internet and didn't find anything about this ANYWHERE, I found this out by chance, stumbling across it by trying to do the heater flaps reset and then by trial and error I discovered what it did.

So you are hearing it here first Be one of the only people in the world to be able to adjust the back lighting on your climate control unit and let me know how it worked for you

DRBC43AMG

Thanks, that's a great find Stick it in the sticky Will give it a try on mine and I'll post my findings

503C43 ////AMG

DONE

JRbro

The codes you are looking for, after holding in REST, are listed near the bottom of the list under: SENSOR VALUE DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION although are really just status codes. As you press the + on the fan control the display flashes the code then its value. Example: 02 then 72 would be the outside temp sensor reading of 72. The procedure below, DIAGNOSTIC TROUBLE CODE READOUT is more telling and shows actual error codes. The "B1" is not displayed with the errors. For example, I am getting 226, 416,417 and 419. In car sensor, coolant circ pump,duovalve left,right, electromagnetic clutch. Hope this helps. Just wish I could figure out why the system is keeping the interior temp 4 degree's above what I have it set for.

DIAGNOSTIC TROUBLE CODE READOUT
Entering Diagnostic Trouble Code (DTC) Display Mode
1) Turn ignition on. Press down arrow push button until "LO" is shown in A/C-heater control panel temperature display window.
2) Within 20 seconds, simultaneously press REST and defrost push buttons for more than 2 seconds. The Light Emitting Diode (LED) in the recirculated air push button will blink and the display window will show "di R".3) Press AUTO push button repeatedly, recording each DTC,until all DTCs are displayed. Permanent malfunctions are displayed first. See DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION tables.
4) If no permanent malfunctions are stored, the display window shows "En d". Press AUTO push button again. Intermittent DTCs will be displayed. Intermittent malfunctions are recognizable by the degree (°) symbol displayed along with the DTC (example: "04 °").
5) If no intermittent malfunctions are stored, the display window shows "En° d". Proceed to ERASING DIAGNOSTIC TROUBLE CODES.

Erasing Diagnostic Trouble Codes
1) After display window shows "En° d", press AUTO push button once again. Display window should show "dE L" (delete).
2) To erase DTCs, simultaneously press down and up arrow push buttons for more than 5 seconds. The display window should show "- --". If not erasing DTCs, press the AUTO push button. The permanent DTCs will again be displayed. Proceed to EXITING DTC DISPLAY MODE.
Exiting DTC Display Mode
Simultaneously press down and up arrow push buttons until the pre-selected temperature setting of "72 °F" is displayed. Turn ignition off.

DTC IDENTIFICATION 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)


READING SENSOR VALUES
1) Turn ignition on. Simultaneously press down and up arrow push buttons until the pre-selected temperature setting of "72 °F" is displayed. Press the AUTO push button.
2) Press REST push button for more than 6 seconds. The display window will alternately show "01" and an in-car temperature of "72 °F", or "LO" if there is an open circuit, or "HI" if there is a short circuit.
3) By pressing the windshield air distribution push button, the next ascending test step is displayed. By pressing the footwell air distribution push button, the next descending test step is displayed. See SENSOR VALUE DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION table. Press REST push button to exit reading sensor values mode.

SENSOR VALUE DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
------------------------------------------------------------
Code Cause/Value
01 ............................. In-Car Temperature Sensor
02 ............................ Outside Temperature Sensor
03 ........................ Heater Core Temperature Sensor
05 .................... Evaporator Core Temperature Sensor
06 ................. (1) Engine Coolant Temperature Sensor
07 .............................. (2) Refrigerant Pressure
08 ............................ (3) Blower Control Voltage
09 .......... Software Status Of A/C-Heater Control Module
15 ........................... Selected In-Car Temperature
20 ................................. Software Version Code
21 ...................................... (4) Engine Speed
22 .............................. (5) A/C Compressor Speed
23 ......................................... Vehicle Speed
50 ................................ 80.° - 00.° (Not Used)
51 ......... Number Of Actual Drive Belt Slip Recognitions
52 ......... Number Of Actual Drive Belt Slip Recognitions
(1) - A display of "12.°5" corresponds to 125 Celsius (257°F).
(2) - Refrigerant pressure is displayed in bar. One bar equals 14.5037 psi. A display of "12.°8" corresponds to 12.8 bar (185.6 psi).
(3) - A display of "16.°5" corresponds to 1.65 volts.
(4) - A display of "06.°0" to "70.°0" corresponds to 600 RPM to 7000 RPM respectively.
(5) - A display of "00.°0" to "84.°0" corresponds to 0 RPM to 8400 RPM respectively.
------------------------------------------------------------
As well, the speed indication is displayed in KPH not MPH!

DRBC43AMG

Excellent and worth copying to the sticky "How To" IMO.

99MBSport

I have a 1999 C280 Sport and I can get the "00" but nothing happens when I push the Up or Down Button Tried it with ignition on and ignition off. Maybe only avail on the C43??? My light in the unit always were dimmer than the others BUT I hguess they'll have to stay that way. Thanks for the info.

siideways

Good info, but unfortunately this doesn't seem to work for C36s. I just followed your directions to the word, but no luck. When I hold down the recirc button, nothing happens. Sucks too, cuz my climate control illumination is really dim compared to my instrumentation cluster.