For 1990-2009 cars

The solid state blower control module controls the blower motor speed on commands from the heater and A/C programmer. The heater and A/C programmer determines the proper blower speed by using information from the following components:

• | The heater and A/C control

• | The network of sensors on the heater and A/C control

• | The steering wheel controls, if equipped.

The heater and A/C programmer sends a blower speed command to the blower control module. This command is a pulse width modulating (PMW) voltage. The blower module reads the PMW from the programmer and translates that voltage into a DC voltage between 4 volts and 12 volts to the blower motor.

The blower may operate in manual or AUTO fan mode.

In the manual fan mode, 6 fan speeds are available. Once the driver selects a fan speed, the fan speed remains constant until a the driver selects a new speed from the heater and A/C controls or the steering wheel controls, if equipped.

In AUTO fan mode, the blower speed is infinitely variable between the minimum and the maximum speeds. The speed varies automatically according to conditions that are monitored by the heater and A/C programmer's network of sensors. This includes the following sensors:

• | The inside air temperature sensor

• | The ambient air temperature sensor

• | The left hand sun load sensor

• | The right hand sun load sensor

• | The coolant sensor

• | The vehicle speed sensor