B1423

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1423: Pressure Sensor Circuit
B1423 - Pressure Sensor Circuit

DESCRIPTION

This DTC is stored when refrigerant pressure is extremely low (0.176 MPa (1.8 kgf/cm2, 25 psi) or less) or extremely high (3.025 MPa (30.9 kgf/cm2, 439 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 A26 air conditioner pressure sensor connector.

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

Standard Voltage:





Text in Illustration





(c) Reconnect the air conditioner pressure sensor connector.

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

2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)





(a) Disconnect the A26 air conditioner pressure sensor connector.

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

Standard Resistance:





Text in Illustration





(c) Reconnect the air conditioner pressure sensor connector.

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

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

(a) Remove the air conditioning amplifier assembly with its connectors still connected Removal.





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

Standard Voltage:





Text in Illustration





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.

(c) Reinstall the air conditioning amplifier assembly.

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

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

(a) Remove the air conditioning amplifier assembly with its connectors still connected Removal.

(b) 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 4.84 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 (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) 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:





Text in Illustration





Result





(c) Reinstall the air conditioning amplifier assembly.

B -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

C -- INSPECT COOLING FAN SYSTEM

A -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

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

(a) Disconnect the A26 air conditioner pressure sensor connector.

(b) Disconnect the D16 air conditioning amplifier assembly connector.

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

Standard Resistance:





(d) Reconnect the air conditioning amplifier assembly connector.

(e) Reconnect the air conditioner pressure sensor connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

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

(a) Disconnect the D16 air conditioning amplifier assembly connector.

(b) Disconnect the A26 air conditioner pressure sensor connector.

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

Standard Resistance:





(d) Reconnect the air conditioner pressure sensor connector.

(e) Reconnect the air conditioning amplifier assembly connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

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

(a) Disconnect the D16 air conditioning amplifier assembly connector.

(b) Disconnect the A26 air conditioner pressure sensor connector.

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

Standard Resistance:





(d) Reconnect the air conditioner pressure sensor connector.

(e) Reconnect the air conditioning amplifier assembly connector.

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

8. CHECK FOR AIR CONDITIONING SYSTEM LEAK

(a) Install the manifold gauge set.

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

(c) Evacuate the air conditioning system and 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





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 (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

OK:

DTC B1423 is not output.

NOTICE:
If the DTC was stored due to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leaks. The root cause of excessive refrigerant may be adding refrigerant when the level was insufficient. Therefore, identify and repair the area where refrigerant leaks as necessary.

NG -- INSPECT AIR CONDITIONER PRESSURE SENSOR

OK -- END

11. INSPECT AIR CONDITIONER PRESSURE SENSOR





(a) Install the manifold gauge set.

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

(c) Turn the ignition switch to ON.

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

Standard Voltage:





Text in Illustration





(e) Reinstall the air conditioning amplifier assembly.

NG -- REPLACE AIR CONDITIONER PRESSURE SENSOR Removal

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. INSPECT COOLING FAN SYSTEM

(a) Inspect that the cooling fan operates normally Testing and Inspection.

NG -- REPAIR COOLING FAN SYSTEM
OK -- Continue to next step.

14. 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 cooler 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.

15. 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 (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) 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 cooler 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 condenser 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 Disassembly

16. 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.

17. CHARGE REFRIGERANT

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

NEXT -- Continue to next step.

18. 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 (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
* If refrigerant pressure is not normal after replacing the cooler expansion valve with a normal one, the condenser or pipes may be clogged due to dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes.

OK:

DTC B1423 is not output.

NG -- REPLACE COOLER CONDENSER ASSEMBLY Removal

OK -- END