On-Vehicle Inspection
WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
INSPECT EVAPORATOR AND FITTINGS FOR LEAKAGE OF REFRIGERANT
Using a gas leak detector, check for leakage of refrigerant.
If there is leakage, check the tightening torque at the joints or check the evaporator.