Blower System
WARNING: This page is about a different car, the 2001 Subaru Impreza and 2000 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
Power to blower relay is controlled by ignition switch. When ignition is turned on and fan switch is operated from 1st to 4th speed, electric current from battery goes through blower motor, resistor, fan switch and ground. Resistor is switched by position of fan switch and controls blower motor speed from 1st to 4th speed.