Temperature control actuator located at heater unit. It contains temp motor that changes temp door position and potentiometer that monitors position of temp door. Temperature control actuator regulates the temperature by the procedure as follows. Signal from control unit adjusts position of temp door by operating temp motor and then temperature will be regulated by the hot/cold air ratio decided by position of temp door. In operation, potentiometer delivers temp door position transformed into voltage value to A/C ECU .
The ECM sets DTC B1204 if there is an open circuit or poor connection in the passenger air mix actuator signal harness.
? Voltage value of Air Mix potentiometer as a function of temp door position.
Door position
Voltage
Error Detecting Condition
Max. cool
0.3±0.15V
Undervoltage : 0.08V or less
Max.warm
4.7±0.15V
Overvoltage : 4.9V or more