K6JRF Auto Page

K6JRF's Page
formerly W6FZC

My Mercedes Benz
S500 Coupe

(Updated: May 21, 2004)

Analyze and Troubleshoot "Check Engine" MIL and Electronic Control Units (ECU)!

Automatic Air Conditioner Diagnostics

Description and Operation
The automatic air conditioner (A/C) in the W140 models can be diagnosed by performing the following steps. There are two (2) basic tests; the first reads the actual sensor values; the second, readout of the DTCs.

The display windows (arrows) show in sequence the actual temperature sensor readings, refrigerant pressure, blower control voltage, software status and control module version.

Reading Sensor Values
The following preparation are required for test:
Air Conditioner control setup - Set the TEMPERATURE selector wheels into the WHITE [white] area.
- Turn Ignition to ON or preferably, start car and let it idle
- Press left and right [AUTO] buttons
- Within 20 seconds, then press [REST] button until the display changes (about 9 secs)
- Number '1' appears in the left window; the in-car temperature in the right ('73 F') as shown in picture, - OR -
HI if there is a short circuit, LO is there is an open circuit.
- By pressing the left [AUTO] button, the next value is displayed in the right window per the table below.
- Press the right [AUTO] button, to go back to the previous value displayed.
- Press [REST] button to end the test program.

Operational Check: - Reading Sensor Values from A/C System
Sensor value readout table, A/C push button control module (N22)

* Display reads only two (2) digits (ex. temperature of 104 deg F reads 04 deg F)
** Displays only if car is equipped with rear A/C
*** As of 2-92

Test Step Sensor Value Display

1 In-car temperature sensor w/ aspirator blower (B10/4)

2 Outside temperature sensor (B10/5)

3 Left heater core temperature sensor (B10/2)*

4 Right heater core temperature sensor (B10/3)*

5 Evaporator temperature sensor (B10/6)

6 Coolant temperature sensor (B10/8)*

7 Refrigerant pressure in bar (06 = 6 bar)

8 Blower control voltage from B(min) - 60(max)

9 Software status, A/C push button control module, manufacturer Bosch: 57, 58, etc.: manufacturer Kammer: 02, 03, etc.

10 ** Left heater core temperature sensor (B10/9) (rear climate control)

11 ** Right heater core temperature sensor (B10/10) (rear climate control)

12 ** Evaporator temperature sensor (B10/11) (rear climate control)

13 ** Software status, rear A/C control unit, manufacturer Bosch: 42 ***

16 Active charcoal filter: R = equipped; O = not equipped

Reading DTCs from Auto A/C System
The following preparation are required for test:
- Set the LEFT TEMPERATURE selector wheel into the RED [red] area.
- Set the RIGHT TEMPERATURE selector wheel into the BLUE [blue] area.
- Turn Ignition to ON.
- Press left [AUTO] button.
- Within 10 seconds, simultaneously press [REST] and [O] buttons until the displays shows permanent stored DTCs in memory per the table below. Press the RIGHT [AUTO] button until all stored DTCs are displayed. Record each as they are displayed.
- Each fault has a specific DTC. The letter 'E' (error) along with the hundredth digit of the display code will show in the window. The tenth and single digit of the code displays in the right window. By pressing the right [AUTO], the next DTC stored in memory will be displayed.
- Turn the ignition OFF and repair recorded DTCs according to the respective diagnostic chart.

- To delete stored DTCs, repeat the first five (5) steps, then press the LEFT [AUTO] for the letter 'D' (delete) to appear in the window. By pressing the right [AUTO] the display code will be deleted from memory. Continue to press the left and right [AUTO] buttons until all codes are deleted from memory. The display will show 'E0 00'.
- Return the temperature selector to normal setting.

Diagnosis - DTCs (fault codes) from the A/C System
Fault table, DTC readout, A/C push button control module (N22)

* Permanent Failure
** Intermittent Failure
*** Possible Sequential Failures 75, 83, 99, 103

Display Code Possible Cause

E0 01 No faults in system

E0 02 A/C push button control module (N22)

E0 03 Rear climate control module

E0 06 Connection to switchover valve block (Y11)

E0 07 Data exchange (CAN B), short circuit

E0 08 Data exchange (CAN A), short circuit

E0 09 Data exchange (CAN A and B), short circuit

E0 10 Repeat displaying for malfunction readout

E0 11 Data exchange (CAN B), open circuit

E0 12 Data exchange (CAN A), open circuit

E0 13 connection to rear climate control module

E0 14 Data exchange (CAN B), open circuit (rear climate control)

E0 15 Data exchange (CAN A), open circuit (rear climate control)

E0 16 In-car temperature sensor w/ aspirator blower (B10/4), short circuit *)

E0 17 In-car temperature sensor w/ aspirator blower (B10/4), short circuit **)

E0 18 In-car temperature sensor w/ aspirator blower (B10/4), open circuit *)

E0 19 In-car temperature sensor w/ aspirator blower (B10/4), open circuit **)

E0 24 Left heater core temperature sensor (B10/2), short circuit *)

E0 25 Left heater core temperature sensor (B10/2), short circuit **)

E0 26 Left heater core temperature sensor (B10/2), open or short circuit *)

E0 27 Left heater core temperature sensor (B10/2), open or short circuit **)

E0 28 Right heater core temperature sensor (B10/3), short circuit *)

E0 29 Right heater core temperature sensor (B10/3), short circuit **)

E0 30 Right heater core temperature sensor (B10/3), open or short circuit *)

E0 31 Right heater core temperature sensor (B10/3), open or short circuit **)

E0 32 Outside temperature sensor (B10/5), short circuit *)

E0 33 Outside temperature sensor (B10/5), short circuit **)

E0 34 Outside temperature sensor (B10/5), open or short circuit *)

E0 35 Outside temperature sensor (B10/5), open or short circuit **)

E0 36 Evaporator temperature sensor (B10/6), short circuit *)

E0 37 Evaporator temperature sensor (B10/6), short circuit **)

E0 38 Evaporator temperature sensor (B10/6), open or short circuit *)

E0 39 Evaporator temperature sensor (B10/6), open or short circuit **)

E0 40 A/C Coolant temperature sensor (B10/8), short circuit *)

E0 41 A/C system coolant temperature sensor (B10/8), short circuit **)

E0 42 A/C system coolant temperature sensor (B10/8), open or short circuit *)

E0 43 A/C system coolant temperature sensor (B10/8), open or short circuit **)

E0 44 Refrigerant pressure sensor (B12), short circuit *)

E0 45 Refrigerant pressure sensor (B12), short circuit **)

E0 46 Refrigerant pressure sensor (B12), open or short circuit *)

E0 47 Refrigerant pressure sensor (B12), open or short circuit **)

E0 48 Left temperature selector wheel, short circuit *)

E0 49 Left temperature selector wheel, short circuit **)

E0 50 Left temperature selector wheel, open or short circuit *)

E0 51 Left temperature selector wheel, open or short circuit **)

E0 52 Right temperature selector wheel, short circuit *)

E0 53 Right temperature selector wheel, short circuit **)

E0 54 Right temperature selector wheel, open or short circuit *)

E0 55 Right temperature selector wheel, open or short circuit **)

E0 72 Heater supply unit circulation pump (A31m1), short circuit *)

E0 73 Heater supply unit circulation pump (A31m1), short circuit **)

E0 74 Heater supply unit circulation pump (A31m1), open or short circuit *)

E0 75 Heater supply unit circulation pump (A31m1), open or short circuit **)

E0 76 Heater supply unit circulation pump (A31m1), over load *)

E0 77 Heater supply unit circulation pump (A31m1), over load **)

E0 80 Heater supply unit left duovalve (A31y1), short circuit *)

E0 81 Heater supply unit left duovalve (A31y1), short circuit **)

E0 82 Heater supply unit left duovalve (A31y1), open or short circuit *)

E0 83 Heater supply unit left duovalve (A31y1), open or short circuit **)

E0 84 Heater supply unit right duovalve (A31y2), short circuit *)

E0 85 Heater supply unit right duovalve (A31y2), short circuit **)

E0 86 Heater supply unit right duovalve (A31y2), open or short circuit *)

E0 87 Heater supply unit right duovalve (A31y2), open or short circuit **)

E0 88 A/C compressor ground activation *)

E0 89 A/C compressor ground activation **)

E0 90 A/C compressor ground activation, open or short circuit *)

E0 91 A/C compressor ground activation, open or short circuit **)

E0 96 Auxiliary fan, 1st activation, short circuit *)

E0 97 Auxiliary fan, 1st activation, short circuit **)

E0 98 Auxiliary fan, 1st activation, open or short circuit *)

E0 99 Auxiliary fan, 1st activation, open or short circuit **)

E1 00 Auxiliary fan, 2nd stage activation, short circuit *)

E1 01 Auxiliary fan, 2nd stage activation, short circuit **)

E1 02 Auxiliary fan, 2nd stage activation, open or short circuit *)

E1 03 Auxiliary fan, 2nd stage activation, open or short circuit **)

E1 04 Auxiliary fan, 3nd stage activation, short circuit *)

E1 05 Auxiliary fan, 3nd stage activation, short circuit **)

E1 06 Auxiliary fan, 3nd stage activation, open or short circuit *)

E1 07 Auxiliary fan, 3nd stage activation, open or short circuit **)

E1 08 After-run pump relay (K30), power supply, short circuit *) ***)

E1 09 After-run pump relay (K30), power supply, short circuit **) ***)

E1 10 After-run pump relay (K30), power supply, open or short circuit *) ***)

E1 11 After-run pump relay (K30), power supply, open or short circuit **) ***)

E1 12 Engine rpm increase diode matrix (V2), short circuit *)

E1 13 Engine rpm increase diode matrix (V2), short circuit **)

E1 14 Engine rpm increase diode matrix (V2), open or short circuit *)

E1 15 Engine rpm increase diode matrix (V2), open or short circuit **)

E1 16 Charcoal filter actuator (A32m2) (OPEN), short circuit *)

E1 17 Charcoal filter actuator (A32m2) (OPEN), short circuit **)

E1 18 Charcoal filter actuator (A32m2) (OPEN), open or short circuit *)

E1 19 Charcoal filter actuator (A32m2) (OPEN), open or short circuit **)

E1 20 Charcoal filter actuator (A32m2) (CLOSED), short circuit *)

E1 21 Charcoal filter actuator (A32m2) (CLOSED), short circuit **)

E1 22 Charcoal filter actuator (A32m2) (CLOSED), open or short circuit *)

E1 23 Charcoal filter actuator (A32m2) (CLOSED), open or short circuit **)

E1 28 Left rear heater core temperature sensor (B10/9), short circuit *)

E1 29 Left rear heater core temperature sensor (B10/9), short circiut **)

E1 30 Left rear heater core temperature sensor (B10/9), short or open *)

E1 31 Left rear heater core temperature sensor (B10/9), short or open **)

E1 32 Right rear heater core temperature sensor (B10/10), short *)

E1 33 Right rear heater core temperature sensor (B10/10), short **)

E1 34 Right rear heater core temperature sensor (B10/10), short or open *)

E1 35 Right rear heater core temperature sensor (B10/10), short or open **)

E1 36 Left temperature selector wheel, short *)

E1 37 Left temperature selector wheel, short **)

E1 38 Left temperature selector wheel, short *)

E1 39 Left temperature selector wheel, short or open **)

E1 40 Right temperature selector wheel, short *)

E1 41 Right temperature selector wheel, short **)

E1 42 Right temperature selector wheel, short or open *)

E1 43 Right temperature selector wheel, short or open **)

E1 44 Right evaporator temperature selector wheel (B10/11), short *)

E1 45 Right evaporator temperature selector wheel (B10/11), short **)

E1 46 Right evaporator temperature selector wheel (B10/11), short or open *)

E1 47 Right evaporator temperature selector wheel (B10/11), short or open **)

E1 48 Coolant circulation pump (A31/1m1), short *)

E1 49 Coolant circulation pump (A31/1m1), short **)

E1 50 Coolant circulation pump (A31/1m1), short or open *)

E1 51 Coolant circulation pump (A31/1m1), short or open **)

E1 52 Coolant circulation pump (A31/1m1), overload *)

E1 53 Coolant circulation pump (A31/1m1), overload **)

E1 56 Left duovalve (water value, A31/1y1, short *)

E1 57 Left duovalve (water value, A31/1y1, short **)

E1 58 Left duovalve (water value, A31/1y1, short or open *)

E1 59 Left duovalve (water value, A31/1y1, short or open **)

E1 60 Right duovalve (water value, A31/1y2, short *)

E1 61 Right duovalve (water value, A31/1y2, short **)

E1 62 Right duovalve (water value, A31/1y2, short or open *)

E1 63 Right duovalve (water value, A31/1y2, short or open **)

E1 64 Rear refrigerant shut-off valve (Y67, short *)

E1 65 Rear refrigerant shut-off valve (Y67, short **)

E1 66 Rear refrigerant shut-off valve (Y67, short or open *)

E1 67 Rear refrigerant shut-off valve (Y67, short or open **)

E1 68 Rear tunnel flap vacuum valve (Y67/1, short *)

E1 69 Rear tunnel flap vacuum valve (Y67/1, short **)

E1 70 Rear tunnel flap vacuum valve (Y67/1, short or open *)

E1 71 Rear tunnel flap vacuum valve (Y67/1, short or open **)

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