Blower Control Module
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
Blower speed is controlled by a Blower Control Module located behind right side of dash, near Blower Motor. Blower Control Module processes a 5-volt Pulse Width Modulated (PWM) voltage signal from Instrument Panel Control Module (IPM) which receives information from A/C-Heater Control Head. The voltage is then amplified by the Blower Control Module to provide variable blower speed.