Heating System H02

Fault code 28

Footwell/defrost valve motor - No reaction to activation, signal unclear

Diagnostic conditions
- Ignition on
- No control module fault stored
- No fault with power supply sensors (5 V) stored

Possible cause of fault
- Short circuit to B+/ground/between one another or open circuit in the wiring between the air-conditioning system regulator and the footwell/defrost valve.
- Footwell/defrost valve stiff
- Servo motor for footwell/defrost valve faulty
- Air-conditioning system regulator faulty

Affected pins
Connector B, pin 3, pin 9, and pin 20
Plug D, pin 3 and pin 11

Diagnosis/troubleshooting