On-Vehicle Inspection

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

Inspect compressor for metallic sound :
Check there is abnormal metallic sound from the compressor when the A/C switch is ON.

If abnormal metallic sound is heard, replace the compressor assembly.
Inspect refrigerant pressure . See 3.
Inspect visually for leakage of refrigerant .
Using a gas leak detector, check for leakage of refrigerant. If there is any leakage, replace the compressor assembly.
Inspect compressor lock sensor resistance :
1. Disconnect the connector.
2. Measure resistance between terminals 2 and 4.
  
  Fig 1: Locating Compressor Lock Sensor Terminals 2 & 4
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Standard resistance: 160 - 320 7 plus or minus; at 20 °C (68 °F).
  
  If resistance is not as specified, replace the sensor.
Check for leakage of grease from clutch bearing .
Check for signs of oil on pressure plate or rotor .
Inspect magnetic clutch bearing for noise :
1. Start engine.
2. Check for abnormal noise from the compressor when the A/C switch is OFF.
  If abnormal noise is being emitted, replace the magnetic clutch.
Inspect magnetic clutch operation :
1. Disconnect the connector.
2. Connect the positive (+) lead form the battery to terminal 1 and the negative (-) lead to the body ground.
  
  Fig 2: Locating Compressor Lock Sensor Terminal 1
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Check that the magnetic clutch energized.
  If operation is not as specified, replace the magnetic clutch.