Air Conditioning System Low Pressure Sensor Circuit

Heater & Air Conditioning System. Lexus Gs430, Gs300. Uzs190 Grs190
Air Conditioning. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT REFRIGERANT PRESSURE

CHECK WIRE HARNESS (LOW PRESSURE SENSOR - A/C AMPLIFIER)

CHECK AIR CONDITIONING AMPLIFIER

INSPECT LOW PRESSURE SENSOR

AIR CONDITIONING SYSTEM - Low Pressure Sensor Circuit


DESCRIPTION

The low pressure sensor is installed on the low-pressure side pipe so that it can detect refrigerant pressure. Then the low pressure sensor sends refrigerant pressure signals to the A/C amplifier, which controls the A/C compressor.

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.Air Conditioning.Air Conditioning System.Air Conditioning System Low Pressure Sensor Circuit


INSPECTION PROCEDURE

1.INSPECT REFRIGERANT PRESSURE

  1. Install the manifold gauge set.

  1. Check that refrigerant is filled in the system by checking the manifold gauge set's pressure readings.

    Standard:
    Refrigerant is filled in system.


NG
ADJUST AMOUNT OF REFRIGERANT
OK


2.CHECK WIRE HARNESS (LOW PRESSURE SENSOR - A/C AMPLIFIER)
Lexus Gs430, Gs300. Uzs190 Grs190.Air Conditioning.Air Conditioning System.Air Conditioning System Low Pressure Sensor Circuit

  1. Disconnect the A51 low pressure sensor connector.

  1. Disconnect the L52 A/C amplifier connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A51-1 (GND) - L52-18 (GND)
    		Always
    		Below 1 Ω
    A51-2 (VOUT) - L52-32 (VOUT)
    		Always
    		Below 1 Ω
    A51-3 (VC) - L52-27 (VC)
    		Always
    		Below 1 Ω
    L52-18 (GND) - Body ground
    		Always
    		10 kΩ or higher
    L52-32 (VOUT) - Body ground
    		Always
    		10 kΩ or higher
    L52-27 (VC) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK AIR CONDITIONING AMPLIFIER
Lexus Gs430, Gs300. Uzs190 Grs190.Air Conditioning.Air Conditioning System.Air Conditioning System Low Pressure Sensor Circuit

  1. Remove the A/C amplifier with its connectors still connected.

  1. Measure the resistance of the connector.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L52-18 (GND) - Body ground
    		Always
    		Below 1 Ω

  1. Measure the voltage of the connector.

    Standard voltage:
    Tester Connection
    		Condition
    		Specified Condition
    L52-27 (VC) - Body ground
    		Engine switch on (IG)
    		10 to 14 V
    Engine switch off
    		Below 1 V


NG
REPLACE AIR CONDITIONING AMPLIFIER
OK


4.INSPECT LOW PRESSURE SENSOR
Lexus Gs430, Gs300. Uzs190 Grs190.Air Conditioning.Air Conditioning System.Air Conditioning System Low Pressure Sensor Circuit

  1. Install the manifold gauge set.

  1. Connect the three 1.5 V dry cell batteries' positive (+) lead to terminal 3 and the negative (-) lead to terminal 1. Then connect the voltmeter's positive (+) lead to terminal 2 and negative (-) lead to terminal 1. Measure the voltage.

    OK:
    The voltage changes according to refrigerant pressure, as shown in the graph.


NG
REPLACE LOW PRESSURE SENSOR
OK

REPLACE AIR CONDITIONING AMPLIFIER