Circuit Description
WARNING: This page is about a different car, the 2004 Toyota Camry Solara. However, it is still accessible from the selected car via links, so may be relevant.
The A/C amplifier outputs the A/C switch ON signal from terminal A/CS and the magnetic clutch ON signal from terminal AC 1 to the ECM. Upon receiving these signals, the ECM sends a signal from terminal ACLD to the A/C amplifier, and switches the magnetic clutch relay on, thus turning the magnetic clutch on.