( TL19E00K733000Y1220FAAT00 )

DTC Troubleshooting: B1220 (L and A/C ON)

1. While checking the same terminal for voltage to ground, reconnect these items individually and note the voltage reading each time:
   - Driver's air mix control motor
   - Passenger's air mix control motor
   - Recirculation control motor
   - Mode control motor

Does the voltage remain at about 5 V?

YES | - | Substitute a known-good heater control unit and recheck. If the symptom/indication goes away, replace the original heater control unit .■
NO | - | Replace the component that caused the voltage drop.■