B0258: HVAC Air Mix Door 1 Circuit

What does B0258 mean?

The HVAC controller reports a fault in the actuator circuit for air mix door 1, which controls the proportion of warm and cool air in the airflow.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Warning light or symbol related to the affected system
• Comfort or safety function impaired

Common causes

• High Air mix door actuator motor failed
• Medium Mix door jammed by debris
• Medium Open wiring to actuator

Likelihood is a general estimate across vehicles; your make and model may differ.