Code 4/26322

Blended air temperature sensor - testing

Fault symptom

Permanent: 46322
Intermittent: 26322

Conditions
Blended air temperature sensor: Open circuit on pin 21 or 22 or 12 V on pin 21 or fault in Automatic Climate Control (ACC) control module monitoring circuit.

Testing

ISAT scan tool command: 252

Display shows:
Blended air temperature = 0° C to +80° C

Display shows fixed temperature +50° C (version 2.00) or a fixed value calculated by ACC control module (version 2.02), fault may be:
Open circuit on pin 21 or 22
Battery positive voltage on pin 22, see "Code 4/22521" Code 4/22521

If the display shows +50° C (version 2.00) or a fixed value calculated by the ACC control module (version 2.01), the fault may be:
Battery positive voltage to pin 21.

If the display shows +80° C (version 2.00 and version 2.01), the fault may be:
Short between pins 21 and 22. (no diagnostic trouble code)
Pin 21 grounded (no diagnostic trouble code).


Important : At temperatures below 0° C, cabin temperature sensor and blended air temperature sensor cannot be tested.


Action
1 Unplug the 39 pin connector from the Automatic Climate Control (ACC) control module and check resistance across pins 21 and 22. Reading varies between 1 and 240 k Ohms within the range +90° - 40° C (194 - 40° F). Some specific readings at various temperatures:

Min. Max.
°C °F (k Ohm) (k Ohm)
0 32 25.5 30.5
+10 50 16.6 19.6
+20 68 11.2 13.0
+30 86 7.7 8.8
+40 104 5.4 6.1

2 If values are incorrect, unplug the temperature sensor connector and repeat the measurement of resistance across pins 9 and 10 on the connector. If the reading is still incorrect, install a new temperature sensor.
3 If the reading is correct across the temperature sensor connector, check if there is an open circuit between connector 98 and the ACC control module'(pins 9 and 21, pins 10 and 22). If not, reinstall the connector, erase all diagnostic trouble codes, restart the system and check if the fault remains.
4 If the fault still remains, measure voltage at pin 21 on the ACC control module. This varies depending on the resistance of the sensor and battery positive voltage according to the following formula: (Measure on connected ACC control module with ignition on.)

(Battery positive voltage - 1.5) x R sensor) / R sensor + 10 k Ohm) = Z

Where Z is the voltage on pin 21.

5 If voltage is too high or too low, try with another ACC control module.