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Diagnostic Manual, Climate Control, Volume 1

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LOCATION:    2.4 Air Conditioning (A/C) (Tempmatic)    >   15 Diagnosis - Diagnostic Trouble Code (DTC) Memory

Diagnosis - Diagnostic Trouble Code (DTC) Memory

Notes regarding Diagnostic trouble Code Memory

To each fault (short circuit, open circuit etc) a certain numerical code has been assigned, i.e. Diagnostic Trouble Code (DTC).
Additionally, current and intermittently appearing DTC's are differentiated from each other.
When retrieving DTC's from the A/C pushbutton control module (N19), short circuits and open circuits can not be differentiated from each other in every case.
If no DTC's are stored in DTC memory, but a complaint exists, it is possible that there may be a problem of incompatible tolerances between components. Since DTC memory can not read these tolerance variations, it is recommended that the entire system be completely checked, using the socket box and multimeter.

Prerequisite for reading out DTC Memory

Electrical wiring diagrams:
Electrical Troubleshooting Manual, Model 170, Group 83

Diagnostic trouble code (DTC)
Possible cause Test step/Remedy 1)
Outside temperature indicator temperature sensor (B14) 23 14.0
Heater core temperature left (B10/1) 23 5.0
Heater core temperature right (B10/2) 23 6.0
Evaporator temperature sensor (B10/6) 23 4.0
ECT sensor (B11/4) 23 14.0
Refrigerant pressure sensor (B12) 23 7.0
Coolant circulation pump (M13) 23 16.0
Left-side water valve (Y21y1) 23 10.0
Right-side water valve (Y21y2) 23 11.0
Electromagnetic clutch (A9k1) 23 9.0
Idle speed regulator 23 15.0
Serial Interface K1 23 14.0
Fresh/recirculated air flap switch over valve (Y13) 23 13.0
Serial Interface K2 23 15.0
1) Observe Preparation for Test, see 22 .