On-Vehicle Inspection

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.

REMOVE LUGGAGE COMPARTMENT FRONT COVER
INSPECT FOR LEAKAGE OF REFRIGERANT
1. Remove the air duct No. 2.
2. Using a gas leak detector, check for leakage of refrigerant from evaporator and joint.
If there is leakage, check the tightening torque at the joints or evaporator.
INSPECT EXPANSION VALVE
1. Check quantity of gas during refrigeration cycle.
2. Set on manifold gauge set.
  
  Fig 1: Checking Leakage Of Refrigerant From Evaporator & Joint
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Run engine.
  1. Run the engine at 1,500 RPM for at least 5 minutes.
  2. Then check that the high pressure reading is 1.37-1.57 Mpa (14-16 kgf.cm² , 199-288 psi).
4. Check expansion valve.
If the expansion valve is faulty, the low pressure reading will drop to 0 kPa (0 kgf.cm² , 0 psi)

HINT:

When the lower pressure drop to 0 kPa (0 kgf.cm² , 0 psi), feel the receiver's IN and OUT sides for no temperature difference.