Heating and Air Conditioning
DTC B1235 or DTC indicator 3: A Problem in the Air Mix Control Linkage, Door, or Motor1. Clear the DTC with the HDS.
2. Operate the heater-A/C control system in several modes.
3. Check for DTCs using the HDS or self-diagnostic.
Is DTC B1235 or 3 indicated?
YES - Go to step 4.
NO - Intermittent failure.
4. Turn the ignition switch OFF.
5. Test the air mix control motor.
Is the air mix control motor OK?
YES - Substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original HVAC control unit
NO - Replace the air mix control motor, or repair the air mix control linkage or door.