PRESSURE SWITCH ON-VEHICLE INSPECTION


  1. INSPECT PRESSURE SWITCH (FOR MAGNETIC CLUTCH CONTROL)

    Tech Tips


    • The pressure switch is installed on the air conditioning pipe on the high pressure side.

    • The pressure switch has two functions. It detects abnormal pressure in the air conditioning cycle and turns the compressor on or off as necessary (magnet clutch control). It also turns the condenser fan on or off in accordance with pressure in the cycle (cooling fan control).

    • The switch on the low pressure side detects a drop in refrigerant pressure, such as from refrigerant leakage, etc. and turns the magnet clutch off (*1) to prevent damage to the compressor.

    • The switch on the high pressure side detects abnormally high pressure in the air conditioning cycle and turns the magnet clutch off (*1) to prevent damage to parts in the air conditioning cycle.

      (*1): The ECM turns the magnet clutch on or off upon receiving the signal from the pressure switch.

    • As the pressure switch operates when there is a malfunction with the refrigerant pressure, its function cannot be inspected on-vehicle. Follow the procedures below to inspect it.


    1. A01BGFSE03

      Inspect refrigerant pressure in air conditioning cycle.

    2. Read the manifold gauge pressure when these conditions are established.

      Test conditions:


      • Temperature at the air inlet with the switch set at RECIRC is 30 to 35°C (86 to 95°F)

      • Engine running at 1,500 rpm

      • Blower speed control switch at "HI" position

      • Temperature control dial at "COOL" position

      • Air conditioning switch ON

      • Fully open doors

      Standard
      Pressure on high pressure side
      1.37 to 1.57 MPa (13.9 to 16.0 kgf*cm2, 198 to 228 psi)

      Tech Tips


      • If the refrigerant pressure is not within the standard value, inspect and repair the air conditioning cycle Click here.

      • Proceed to step (b) if the refrigerant pressure is within the specified range.

      • If the refrigerant pressure is below 196 KPa (2.0 kgf*cm2, 28 psi), the refrigerant amount in the air conditioning cycle may have decreased significantly for reasons such as a gas leakage.

    3. A01BBS2E01

      Check air conditioning operation.


      1. Disconnect the pressure switch connector.

      2. Connect terminals 1 and 4 of the connector of the pressure switch on the vehicle wire harness side using a service wire.

      3. Start the engine.

      4. Turn the air conditioning switch on and check that the magnet clutch is turned on.

      5. Check that the magnet clutch is turned off when disconnecting terminals 1 and 4 (that are connected in the prior step).

        Standard
        Terminals 1 and 4 connected
        magnet clutch is on
        Terminals 1 and 4 disconnected
        clutch is off

        Replace the pressure switch if the magnet clutch is operated normally.

        Inspect and repair the wire harness between the pressure switch and the ECM.

  2. INSPECT PRESSURE SWITCH (FOR COOLING FAN CONTROL)

    Tech Tips

    The switch turns the condenser fan on or off in accordance with pressure in the cycle so that heat exchange in the condenser can be effectively within the normal pressure range.


    1. Install the manifold gauge.

    2. Disconnect the pressure switch connector and connect terminals 1 and 4 using a tool such as a service wire.

    3. Connect the positive (+) lead from the ohmmeter to terminal 2 and the negative (-) lead to terminal 3.

    4. Start the engine and turn the air conditioning switch on.

    5. A01BES6E01

      Check that the continuity between terminals 2 and 3 changes in accordance with the refrigerant pressure as shown in the illustration on the left.

      OK
      Changes in accordance with the refrigerant pressure as shown in the illustration.

      If the operation is not as specified, replace the pressure switch.