Air Conditioning System (For Automatic Air Conditioning System)

AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): B1423/23: Pressure Sensor Circuit
B1423/23 - Pressure Sensor Circuit

DESCRIPTION

This DTC is stored when refrigerant pressure is extremely low (0.176 MPa [1.8 kgf/cm2, 25.5 psi] or less) or extremely high (3.025 MPa [30.9 kgf/cm2, 438.6 psi] or more). The air conditioner pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the air conditioning amplifier. The air conditioning amplifier converts the 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 stored if there is no refrigerant in the cycle.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the A21 air conditioner pressure sensor connector.

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

Standard Voltage:

NG -- CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.

2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)

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

Standard Resistance:

NG -- CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.

3. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Reconnect the A21 air conditioner pressure sensor connector.

(b) Remove the air conditioning amplifier with its connectors still connected.

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

Standard Voltage:

HINT
If the measured voltage is not within the normal range, there may be a malfunction in the air conditioning amplifier assembly, air conditioner pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

NG -- CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.

4. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Measure the voltage when the following conditions are satisfied.

Measurement Condition

NOTICE:
* If refrigerant pressure on the high pressure side becomes extremely high during the inspection (if the voltage exceeds 4.8 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe operation.
* It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the problem symptom may recur after a while.

HINT
When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

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

Standard Voltage:

NG -- CHARGE REFRIGERANT

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

5. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)

(a) Disconnect the E37 air conditioning amplifier connector.

(b) Disconnect the A21 air conditioner pressure sensor connector.

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

Standard Resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

6. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

7. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

8. INSPECT FOR AIR CONDITIONING SYSTEM LEAK

(a) Install a manifold gauge set.

(b) Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.

(c) Check that vacuum can be maintained in it.

OK:

Vacuum can be maintained in the air conditioning system.

HINT
If vacuum cannot be maintained in the air conditioning system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the air conditioning system.

NG -- REPAIR AIR CONDITIONING SYSTEM LEAK
OK -- Continue to next step.

9. CHARGE REFRIGERANT

(a) Add an appropriate amount of refrigerant Service and Repair.

NEXT -- Continue to next step.

10. RECHECK DTC

(a) Recheck for the DTC when the following conditions are satisfied.

Measurement Condition

(a) Install a manifold gauge set.

(b) Reconnect the A21 air conditioner pressure sensor connector.

(c) Remove the air conditioning amplifier with its connectors still connected.

(d) Turn the ignition switch ON.

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

Standard Voltage:

NG -- REPLACE AIR CONDITIONER PRESSURE SENSOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

12. REPAIR AIR CONDITIONING SYSTEM LEAK

(a) Identify the area where refrigerant leaks Service and Repair.

(b) Repair the identified area of the air conditioning system.

(c) Evacuate the air conditioning system.

NEXT -- CHARGE REFRIGERANT Service and Repair

13. CHARGE REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the air conditioning system.

(c) Add an appropriate amount of refrigerant Service and Repair.

HINT
If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

NEXT -- Continue to next step.

14. RECHECK DTC

(a) Recheck for the DTC when the following conditions are satisfied.

Measurement Condition

NOTICE:
If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning system operates for a while.

HINT
* When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
* If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC. If the DTC is not output after this procedure, it indicates that the cooler dryer in the cooler condenser assembly is not able to absorb moisture in the refrigerant cycle. In this case, to complete the repair it is necessary to replace the cooler dryer.

OK:

DTC B1423 is not output.

NG -- REPLACE COOLER EXPANSION VALVE

OK -- REPLACE COOLER DRYER Removal

15. REPLACE COOLER EXPANSION VALVE

(a) Replace the cooler expansion valve with a normal one Disassembly.

HINT
Replace the cooler expansion valve with a normal one because the cooler expansion valve is either stuck or clogged.

NEXT -- Continue to next step.

16. CHARGE REFRIGERANT

(a) Add an appropriate amount of refrigerant Service and Repair.

NEXT -- Continue to next step.

17. RECHECK DTC

(a) Recheck for the DTC when the following conditions are satisfied.

Measurement Condition