Test step display	Possible Cause	Test Step/Remedy 1)
	In - car temperature sensor	23 1.0
	Outside temperature sensor	23 2.0
	Evaporator temperature sensor	23 3.0
	Heater core temperature sensor	23 4.0
	ECT sensor	23 5.0
	Temperature selector wheel setting (oC)	A/C pushbutton control module
	Vehicle speed (km/h)	DM, Body and Accessories, Vol. 3 - 11.2
	Soft top open , soft top closed	23 14.0
	System voltage	23 16.0 - 17.0
	OFF/ON (not used)	-
2)	Blower voltage (0.5 V) - (6.0 V)	23 22.0

1) Observe Preparation for Test, see 22 . 2) Starting approximately 11/91.

Test preparations for test modes B. and C. Turn temperature selector wheel to white field. Turn ignition " ON " and within 10 seconds press , and simultaneously for 2 to 4 seconds. The display will show permanent DTC's stored in memory. After each DTC is displayed and recorded, press again until the display reads . Press once again. Now the stored intermittent DTC's will be displayed. The symbol will appear after each DTC to indicate an intermittent fault. After each DTC is displayed and recorded, press again unttil the dissplay reads . Press once again. The display will alternately blink the number and the in - car temperature in oC. Press until all temperature sensor display numbers from - are shown (see section C). Press once again and the display will alternately blink the number and the voltage of the potentiometer for the center air outlet flap dependent upon the setting (open or closed). The voltage, for example, for 3.5 V is displayed as . Press until all potentiometer and feedback potentiometer display numbers from - are shown. Press until the display reads " " and the symbol blinks. Turn ignition OFF and repair recorded DTC's. Note: The DTC's can be redisplayed as often as desired. To do so, turn ignition OFF and ON and within 10 seconds press , and simultaneously for 2 to 4 seconds and then press only . The light diode inside will blink once per second during the impulse readout. Erasing DTC's Turn ignition ON and within 10 seconds press , and simultaneously for 2 to 4 seconds until "- - -" appears on the display. Verification Repeat readout of DTC's. The number (no fault) must appear in the display window. Electrical Wiring Diagrams: See "Electrical Troubleshooting Manual", Model 129

B. DTC readout with permanent and intermittent faults

Diagnostic Trouble Code (DTC)	Possible Cause	Test Step/Remedy 1)
	No stored DTC's in system memory	-
	In - car temperature sensor (B10/4), short circuit	23 1.0
	In - car temperature sensor (B10/4), open circuit	23 1.0
	Outside temperature sensor (B10/5), short circuit	23 2.0
	Outside temperature sensor (B10/5), open circuit	23 2.0
	Evaporator temperature sensor (B10/6), short circuit	23 3.0
	Evaporator temperature sensor (B10/6), open circuit	23 3.0
	Heater core temperature sensor (B10/1), short circuit	23 4.0
	Heater core temperature sensor (B10/1), open circuit	23 4.0
	ECT sensor (B10/8), short circuit	23 5.0
	ECT sensor (B10/8), open circuit	23 5.0
	Center air outlet adjuster (N18/2r2), short circuit	23 7.0
	Center air outlet adjuster (N18/2r2), open circuit	23 7.0
	Center air outlet feedback potentiometer (R23/3), short circuit	23 12.0
	Center air outlet feedback potentiometer (R23/3), open circuit	23 12.0
	Left air outlet adjuster (N18/2r1), short circuit	23 6.0
	Left air outlet adjuster (N18/2r1), open circuit	23 6.0
	Left air outlet feedback potentiometer (R23/1), short circuit	23 11.0
	Left air outlet feedback potentiometer (R23/1), open circuit	23 11.0
	Right air outlet adjuster (N18/2r3), short circuit	23 8.0
	Right air outlet adjuster (N18/2r3), open circuit	23 8.0
	Right air outlet feedback potentiometer (R23/2), short circuit	23 13.0
	Right air outlet feedback potentiometer (R23/2), open circuit	23 13.0
	Auxiliary coolant pump (M13), short circuit	23 20.0
	Automatic A/C monovalve (Y19), short circuit	23 19.0
	A/C compressor signal, short circuit	23 25.0
	Auxiliary fan signal, 2nd stage, short circuit	23 24.0
	Auxiliary fan signal, 1st stage, short circuit	23 23.0
	Not used	-
	Switchover valve block (Y11), short circuit	23 21.0
	Auxiliary coolant pump (M13), open circuit	23 20.0
	Automatic A/C monovalve (Y19), open circuit	23 15.0
	A/C compressor signal, open circuit	23 25.0
	Auxiliary fan signal, 2nd stage, open circuit	23 24.0
	Auxiliary fan signal, 1st stage, open circuit	23 23.0

1) Observe Preparation for Test, see 22 .

C. Readout of momentary sensor temperatures as well as potentiometer and feedback potentiometer voltages.

Test step	Test scope	Test connection	Nominal value	Test step/Remedy
	In - car temperature sensor	Press	Indicated value may deviate by no more than ± 1 oC	23 1.0
	Outside temperature sensor	Press	Indicated value may deviate by no more than ± 3 oC	23 2.0
	Evaporator temperature sensor	Press	Indicated value may deviate by no more than ± 3 oC	23 3.0
	Heater core temperature sensor	Press	Indicated value may deviate by no more than ± 3 oC	23 4.0
	ECT sensor	Press	Indicated value may deviate by no more than ± 3 oC	23 6.0
	Center air outlet adjuster	Move center air outlet adjuster completely to the right (outlet closed) Move center air outlet adjuster completely to the left (outlet open)	- 0.6 - 0.9 V - 3.9 - 4.5 V	23 8.0
	Center air outlet feedback potentiometer	Move center air outlet adjuster completely to the right (outlet closed) Move center air outlet adjuster completely to the left (outlet open)	- 0.7 - 1.1 V - 3.5 - 4.8 V	23 13.0
	Left air outlet adjuster	Move left air outlet adjuster completely to the right (outlet closed) Move left air outlet adjuster completely to the left (outlet open)	- 0.6 - 0.9 V - 3.9 - 4.5 V	23 7.0
	Left air outlet feedback potentiometer	Move left air outlet adjuster completely to the right (outlet closed) Move left air outlet adjuster completely to the left (outlet open)	- 0.7 - 1.1 V - 3.5 - 4.8 V	23 12.0
	Right air outlet adjuster	Move right air outlet adjuster completely to the right (outlet closed) Move right air outlet adjuster completely to the left (outlet open)	- 0.6 - 0.9 V - 3.9 - 4.5 V	23 9.0
	Right air outlet feedback potentiometer	Move right air outlet adjuster completely to the right (outlet closed) Move right air outlet adjuster completely to the left (outlet open)	- 0.7 - 1.1 V - 3.5 - 4.8 V	23 14.0