B1423

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

DESCRIPTION

This DTC is stored when the 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 higher). The air conditioner pressure sensor, which is installed on the pipe of the high pressure side to detect the refrigerant pressure, outputs the refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts the signal to a pressure value 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 may also be stored if there is no refrigerant in the cycle.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - BATTERY)

(a) Disconnect the A12 sensor connector.





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

Standard Voltage:





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

Standard Resistance:





Text in Illustration





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

2. CHECK 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.

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

3. CHECK 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 met.

Measurement Condition





NOTICE:
* If the refrigerant pressure on the high pressure side becomes extremely high during the inspection (the voltage exceeds 4.8 V), the fail-safe function stops the 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 the operation of the thermistor assembly and 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 -- CHECK COOLING FAN SYSTEM

B -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

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

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

(a) Disconnect the A12 sensor connector.

(b) Disconnect the C32 amplifier 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

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

(a) Disconnect the A12 sensor connector.

(b) Disconnect the C32 amplifier connector.

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

Standard Resistance:





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

6. CHECK 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 Service and Repair.

(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.

7. CHARGE REFRIGERANT

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

NEXT -- Continue to next step.

8. CHECK FOR DTC

(a) Check for DTCs when the following conditions are met Reading and Clearing Diagnostic Trouble Codes.

Measurement Condition





NOTICE:
If the refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed 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 the operation of the thermistor assembly and 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 leakage. Therefore, identify and repair the area where refrigerant leaks as necessary. The root cause of excessive refrigerant may be adding too much refrigerant.

NG -- CHECK AIR CONDITIONER PRESSURE SENSOR

OK -- END (AMOUNT OF REFRIGERANT IS INCORRECT)

9. CHECK AIR CONDITIONER PRESSURE SENSOR

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





(b) Install a manifold gauge set.

(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





NG -- REPLACE AIR CONDITIONER PRESSURE SENSOR Removal

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

10. 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

11. CHECK COOLING FAN SYSTEM

(a) Check if the cooling fan system is functioning properly Testing and Inspection.

OK:

Cooling fan system is functioning properly.

NG -- GO TO COOLING FAN SYSTEM Testing and Inspection
OK -- Continue to next step.

12. CHARGE REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant Service and Repair.

(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 then check for DTCs.

NEXT -- Continue to next step.

13. CHECK FOR DTC

(a) Check for DTCs when the following conditions are met Reading and Clearing Diagnostic Trouble Codes.

Measurement Condition





NOTICE:
If the refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed 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 the operation of the thermistor assembly and 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 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 DTCs. If the DTC is not output after this procedure, it indicates that the cooler dryer in the condenser assembly with receiver 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

14. REPLACE COOLER EXPANSION VALVE

(a) Temporarily replace the cooler expansion valve with a new or normally functioning one Removal.

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

NEXT -- Continue to next step.

15. CHARGE REFRIGERANT

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

NEXT -- Continue to next step.

16. CHECK FOR DTC

(a) Check for DTCs when the following conditions are met Reading and Clearing Diagnostic Trouble Codes.

Measurement Condition





NOTICE:
If the refrigerant pressure on the high pressure side becomes high, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed 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 the operation of the thermistor assembly and No. 1 cooler thermistor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.
* If the refrigerant pressure is not normal after replacing the expansion valve with a new or normally functioning one, the cooler condenser assembly or pipes may be clogged due to dirt, dust or other contaminants. In this case, clean or replace the condenser assembly with receiver or the pipes.

OK:

DTC B1423 is not output.

NG -- CLEAN OR REPLACE CONDENSER ASSEMBLY WITH RECEIVER OR PIPES Removal

OK -- END (COOLER EXPANSION VALVE IS FAULTY)