DTC B1423/23 Pressure Switch Circuit

DESCRIPTION

This DTC is output when refrigerant pressure is extremely low (0.19 MPa (2.0 kgf/cm², 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm², 455 psi) or more). The pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs a refrigerant pressure signal to the A/C amplifier. The A/C amplifier converts this signal to pressure according to the sensor characteristics to control the compressor.

HINT:

Be sure to check the refrigerant volume first when this DTC is output because this DTC can also be output if there is no refrigerant in the system.

DTC No.	DTC Detection Condition	Trouble Area
B1423/23	Open or short in pressure switch circuit	Pressure sensor Harness and connector between pressure sensor and A/C amplifier Refrigerant pipe line A/C amplifier

WIRING DIAGRAM

Dtc B1423/23 Pressure Switch Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

1.CHECK REFRIGERANT

Dtc B1423/23 Pressure Switch Circuit. AIR CONDITIONING. Lexus IS250 IS220d GSE20 ALE20

Check the sight glass of the cooler unit refrigerant liquid pipe.

Prepare the vehicle according to the chart below.

Item	Condition
Vehicle Doors	Fully open
Temperature Setting	MAX COLD
Blower Speed	HI
A/C	ON

Compare the sight glass to the following chart.

Item	Symptom	Amount of Refrigerant	Corrective Actions
1	Bubbles visible	Insufficient*	Check for gas leakage and repair if necessary Add refrigerant until bubbles disappear
2	No bubbles visible	Empty, insufficient, or excessive	Refer to 3 and 4
3	No temperature difference between compressor inlet and outlet	Empty or nearly empty	Check for gas leakage with gas leak detector and repair if necessary Evacuate A/C system and recharge with proper amount of refrigerant
4	Considerable temperature difference between compressor inlet and outlet	Proper or excessive	Refer to 5 and 6
5	Immediately after air conditioning is turned OFF, refrigerant clears	Excessive	Recover refrigerant Evacuate A/C system and recharge with proper amount of refrigerant
6	Immediately after air conditioning is turned OFF, refrigerant foams and then becomes clear	Proper	-

^*: Bubbles in the sight glass with the vehicle interior temperature above 35°C (95°F) can be considered normal if cooling is sufficient.

NG

CHARGE REFRIGERANT

OK

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

Disconnect the pressure sensor connector.

Disconnect the A/C amplifier connector.

Measure the resistance according to the value(s) in the table below.

Standard resistance:

Tester Connection	Condition	Specified Condition
B7-2 (PR) - J58-13 (PRE)	Always	Below 1 Ω
B7-3 (+) - J58-26 (S5-2)	Always	Below 1 Ω
B7-1 (-) - J58-38 (SG-2)	Always	Below 1 Ω
J58-13 (PRE) - Body ground	Always	10 kΩ or higher
J58-26 (S5-2) - Body ground	Always	10 kΩ or higher
J58-38 (SG-2) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.INSPECT PRESSURE SENSOR

Install the manifold gauge set .

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

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

Result:
Result Proceed to
NG A
OK (When troubleshooting according to the DTC) B
OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE) C

B

REPLACE AIR CONDITIONING AMPLIFIER

C

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

A

REPLACE PRESSURE SENSOR

LEXUS IS250, IS220d / GSE20 ALE20

AIR CONDITIONING

Lexus IS250 IS220d GSE20 ALE20

AIR CONDITIONING SYSTEM

Result	Proceed to
NG	A
OK (When troubleshooting according to the DTC)	B
OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE)	C