1.When IG1 relay No.2 turns ON, the blower relay turns ON (1).
2.When the blower relay turns on, the blower fan controller goes on operation stand-by (2).
3.When the blower relay turns on, the climate control unit sends (4) an airflow volume setting signal to the blower fan controller based on the airflow volume setting (3).
4.The blower fan controller drive circuit determines (5) the duty ratio to rotate the blower motor, based on the airflow volume setting signal, and turns the power MOS FET (6) on or off.
5.When the power MOS FET is turned on, the blower motor circuit is established (7) and the blower motor rotates (8).
6.The power MOS FET repeatedly turns on or off at high speed to suppress the blower motor and control the rotation speed.
7.When the blower motor rotates, airflow is sent to the A/C unit. In addition, the air intake door is either at FRESH or RECIRCULATE depending on the air intake door position.