B0278HVAC Defrost Door Circuit
- Generic OBD-II code · Body
- How the car detects it
- B0278 appears neither in J2012 tables nor in factory service material, so its existence is open. By its title it covers the electrical side of the defrost door actuator, the flap that routes air to the windscreen. Saab's 9-3 climate module stores the matching fault as B0240 06 (actuator circuit open or grounded) and B0241 01 (short to battery or excessive current); both lead to wrong air distribution. Hitachi's US5181553A drives the defroster door with a dedicated actuator motor, and MOTOR magazine describes how such actuators are tested electrically. A dead circuit leaves the door parked, so demisting may be weak or air may blow at the screen constantly. Door position problems without an electrical fault fit B0205.
- What you may notice
- Windscreen clears slowly because little air reaches it
- Air keeps blowing at the windscreen whatever mode is selected
- Likely causes
- LikelyDefrost door actuator motor open or shorted internally
- PossibleActuator wiring under the dashboard damaged or connector loose
- RareDoor or linkage seized so the motor draws excessive current
- RareActuator driver in the climate control module failed
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.