Heater Water Control Valve
WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect heater water control valve cable, located in heater inlet line near firewall. Turn ignition on. Press A/C button. Set temperature control knob to maximum cool position (counterclockwise). Set heater water control valve to cool position. Install control cable, and secure with clamp. See Fig 1.