Blower Motor Circuit: Description
WARNING: This page is about a different car, the 2011 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
When the No. 2 heater control (blower switch) is operated, the HTR relay will turn on and send current to operate the blower motor. Operating the No. 2 heater control (blower switch) adjusts the flow of current between the blower resistor and body ground, thus, adjusting the speed of the blower motor.