Circuit Description
WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.
The blower motor is operated by signals from the A/C ECU.
Blower motor speed signals are transmitted by changes in the Duty Ratio.
Duty Ratio
The duty ratio is the ratio of the period of continuity in one cycle.
For example, if A is the period of continuity in one cycle, and B is the period of non-continuity, then.