What does it mean?
B1236 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Open in the Passenger's Air Mix Control Motor Circuit .
Symptoms
- Passenger side vents deliver only hot or only cold air regardless of the setting
- The passenger temperature control has no effect while the driver side responds normally
- No actuator movement can be heard behind the glove box when the setting is changed
- Cabin temperature is uneven and the front passenger cannot get comfortable
- On single zone systems the entire cabin temperature may be affected
Likely causes
- Broken wire in the harness running to the passenger side blend actuator
- Actuator connector unplugged or a terminal backed out of its housing
- Open motor winding or a broken feedback track inside the passenger blend actuator
- Corroded terminals after water entered from a blocked evaporator drain
- Harness pulled or cut during glove box, blower motor, or evaporator work
- Failed output driver in the climate control module
How to fix it
- Command the passenger blend actuator with a scan tool and listen for movement behind the glove box
- Check for a drive voltage on the control pins at the actuator connector while it is being commanded
- Measure the actuator motor winding and feedback potentiometer for continuity out of circuit
- Verify that ground and the reference voltage are present at the connector
- Test continuity of each control wire from the actuator back to the climate module and repair any open
- Replace the actuator if it measures open, run the calibration routine, and confirm the vent temperature changes