What does it mean?
B1233 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Open in the Driver's Air Mix Control Motor Circuit .
Symptoms
- Driver side vents blow only hot or only cold no matter what temperature is set
- The temperature dial has no effect on the driver side while the passenger side still works
- No actuator movement can be heard when the temperature setting is swept
- Footwell and defrost temperature cannot be managed in cold weather
- Cabin comfort is very uneven from side to side on dual zone systems
Likely causes
- Broken wire between the driver side blend actuator and the climate control module
- Actuator connector unplugged or a terminal backed out of its housing
- Internally open motor winding or a broken feedback potentiometer track inside the actuator
- Worn internal contacts or a broken solder joint in the actuator after years of travel
- Harness chafed through where it passes over a bracket under the dash
- Failed output driver in the climate control module
How to fix it
- Command the driver blend actuator with a scan tool and listen for movement at the HVAC case
- Unplug the actuator and check for a drive signal on the control pins while it is commanded
- Measure the actuator motor winding and feedback potentiometer for continuity, where an open reading condemns the unit
- Verify the ground and the reference voltage present at the actuator connector
- Trace and repair any open wire between the actuator and the climate control module
- Replace the blend actuator if it measures open, then run the climate calibration so the door end stops are relearned