STEP 1. Using scan tool MB991958, check actuator test of A/C controller assembly (A/C-ECU) check.
STEP 2. Check open and short circuit in DEF and FACE line between mode selection damper control motor and potentiometer connector (mode selection damper control motor side) and auto A/C controller assembly (A/C-ECU) connector
STEP 3. Check the mode selection damper control motor and potentiometer.
STEP 4. Check whether the diagnostic trouble code is stored again.