B1423

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1423/23: Pressure Sensor Circuit
B1423/23 - Pressure Sensor 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 the refrigerant pressure signal to the front controller. The front controller sends the read signal to the air conditioning amplifier via the CAN communication line. 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 output if there is no refrigerant in the cycle.
* This circuit uses the CAN communication line. Before performing the inspection, check that the CAN communication system is functioning normally.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the B4 pressure sensor connector.





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

Standard voltage:





NG -- CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)
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 (FRONT CONTROLLER - PRESSURE SENSOR)
OK -- Continue to next step.

3. CHECK PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Reconnect the B4 pressure sensor connector.

(b) Remove the front controller 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 front controller, pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

NG -- CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)
OK -- Continue to next step.

4. CHECK PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

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





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 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 -- INSPECT COOLING FAN SYSTEM

OK -- REPLACE FRONT CONTROLLER

5. CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)

(a) Disconnect the B14 front controller connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE FRONT CONTROLLER

6. CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)

(a) Disconnect the B14 front controller connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE FRONT CONTROLLER

7. CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)

(a) Disconnect the B14 front controller connector.





(b) Disconnect the B4 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 -- Continue to next step.

8. INSPECT FOR A/C SYSTEM LEAK

(a) Install the manifold gauge set.

(b) Recover the refrigerant from the A/C system using a refrigerant recovery unit.

(c) Evacuate the A/C system and check that vacuum can be maintained in it.

OK:

Vacuum can be maintained in the A/C system.

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

NG -- REPAIR A/C 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.





NOTICE:
If refrigerant pressure on the high pressure side becomes high, the DTC will be set. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C 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.

Result





NOTICE:
If the DTC was set 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.

B -- END (EXPANSION VALVE IS DEFECTIVE)
A -- Continue to next step.

11. CHECK PRESSURE SENSOR

(a) Install the manifold gauge set.





(b) Reconnect the B4 sensor connector.

(c) Reconnect the B14 front controller connector.

(d) Remove the front controller with its connectors still connected.

(e) Turn the power switch on (IG).

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

Standard voltage:





NG -- REPLACE PRESSURE SENSOR Replacement

OK -- REPLACE FRONT CONTROLLER

12. REPAIR A/C SYSTEM LEAK

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

(b) Repair the identified area of the A/C system.

(c) Evacuate the A/C system.

NEXT -- CHARGE REFRIGERANT Service and Repair

13. INSPECT COOLING FAN SYSTEM

(a) Inspect that the cooling fan operates normally Cooling Fan Circuit.

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

14. CHARGE REFRIGERANT

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

(b) Evacuate the A/C 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.

15. RECHECK DTC

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





NOTICE:
If refrigerant pressure on the high pressure side becomes high, the DTC will be set. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C 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 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.

Result





B -- REPLACE COOLER DRYER Removal
A -- Continue to next step.

16. REPLACE EXPANSION VALVE

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

HINT
Replace the expansion valve with a normal one because the 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.





NOTICE:
If refrigerant pressure on the high pressure side becomes high, the DTC will be set. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C 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 pressure is not normal after replacing the 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.

Result





B -- REPLACE CONDENSER Removal

A -- END (EXPANSION VALVE IS DEFECTIVE)