On-Vehicle Inspection

WARNING: This page is about a different car, the 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

SET ON MANIFOLD GAUGE SET (See MANIFOLD GAUGE SET )
DISCONNECT CONNECTOR FROM PRESSURE SWITCH
RUN ENGINE AT APPROX. 1,500 RPM

Fig 1: Identifying Pressure Switch Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Magnetic clutch control:
INSPECT PRESSURE SWITCH OPERATION
1. Connect the positive (+) lead from the ohmmeter to terminal 4 and the negative (-) lead to terminal 1.
2. Check continuity between terminals when refrigerant pressure is changed.
  If operation is not as specified, replace the pressure switch.
  
  Fig 2: Inspecting Pressure Switch Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Cooling fan control:
INSPECT PRESSURE SWITCH OPERATION
1. Connect the positive (+) lead from the ohmmeter to terminal 2 and the negative (-) lead to terminal 3.
2. Check continuity between terminals when refrigerant pressure is changed.
If operation is not as specified, replace the pressure switch.
STOP ENGINE AND SET OFF MANIFOLD GAUGE SET
CONNECT CONNECTOR TO PRESSURE SWITCH