Automatic Climate Control

FAULT DIAGNOSIS HINTS
When taking readings and during fault diagnosis, the connector must be removed. All readings must be taken on the connector and not on the climate control unit. With the exception of changing bulbs, the unit must not be tampered with.

Self-diagnostics
There is a special self-test program in the climate control unit's microprocessor.

The program regularly checks certain functions during driving, and an emergency program is activated if there is a fault in any of the sensors.

Faults detected by the self-test program are stored as diagnostic trouble codes in the memory of the microprocessor. Diagnostic trouble codes are read using the ISAT scan tool.

Calibration
The flap actuator motors must be calibrated at the following times:
^ After changing the control panel.
^ After changing the flap motors.
^ If the battery has been removed within 30 seconds of the ignition being switched off.
^ If the battery has been discharged or if battery positive voltage has been higher than 15 V.

Calibration is carried out either by simultaneously pressing the AUTO and <=> buttons or by means of the ISAT scan tool.

A self-test is carried out in conjunction with calibration. The total time for calibration and self-test is 22-50 seconds. The number of faults (0-5), if any, is shown in the display during the first 35 seconds.

Other Fault Diagnosis
1. Check that the relevant fuses are intact and supplied with current.
2. Check the interior temperature sensor suction fan by allowing a thin piece of paper to be sucked onto the intake.
3. Check the climate control unit connectors. Clean by unplugging and plugging them in again.
4. Check the connectors, wiring harness and ground connections.

For checking A/C compressors and radiator fans.

Resistances, blended air temperature sensor

Minimum Maximum
(Kohm) (Kohm)
+/-0°C 25.5 30.5
+ 10°C 16.6 19.6
+ 20°C 11.2 13.0
+ 30°C 7.7 8.8
+ 10°C 5.4 6.1

Interior temperature sensor

Minimum Maximum
(Kohm) (Kohm)
+/- 0°C 30.0 34.8
+ 10°C 18.5 21.1
+ 20°C 11.7 13.1
+ 25°C 9.5 10.5
+ 30°C 7.6 8.5
+ 40°C 4.9 5.6