B1423

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1423/23: Pressure Sensor Circuit
B1423/23 - Pressure Sensor Circuit

DESCRIPTION

This DTC is stored when refrigerant pressure on the high pressure side 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 A/C pressure sensor is installed on the high pressure line. It detects refrigerant pressure to output a refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts this signal to a pressure value according to the sensor characteristics to control the compressor.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the A/C pressure sensor connector.

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

Standard Voltage:

NG -- CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C 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 (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR)
OK -- Continue to next step.

3. INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Reconnect the A/C pressure sensor connector.

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

HINT
If the voltage is not as specified, there may be a malfunction in the air conditioning amplifier assembly, A/C pressure sensor or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

Text in Illustration

NG -- CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR)
OK -- Continue to next step.

4. INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Measure the voltage when the following conditions are met:

NOTICE:
* If refrigerant pressure on the high pressure line 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 function operates.
* It is necessary to measure the voltage over a period 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 signals from 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:

Result:

Text in Illustration

C -- INSPECT COOLING FAN SYSTEM

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

A -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

5. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR)

(a) Disconnect the air conditioning amplifier assembly 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 AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

6. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR)

(a) Disconnect the air conditioning amplifier assembly 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 AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

7. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR)

(a) Disconnect the air conditioning amplifier assembly connector.

(b) 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. CHECK 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.

OK:

Vacuum can be maintained in the A/C system.

HINT
If vacuum cannot be maintained in the A/C system, there may be a refrigerant leak. 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 FOR DTC

(a) Recheck for the DTC when the following conditions are met:

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 any refrigerant leaks as necessary.

B -- END
A -- Continue to next step.

11. INSPECT A/C PRESSURE SENSOR

(a) Install the manifold gauge set.

(b) Reconnect the A/C pressure sensor connector.

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

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

Standard Voltage:

HINT
The A/C pressure sensor power source voltage is 5 V.

Text in Illustration

NG -- REPLACE A/C PRESSURE SENSOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

12. REPAIR A/C SYSTEM LEAK

(a) Identify the area where refrigerant leaks from 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) Check that the cooling fan(s) operates normally.

HINT
Refer to Cooling Fan Circuit Cooling Fan Circuit.

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 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, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for DTCs.

NEXT -- Continue to next step.

15. RECHECK FOR DTC

(a) Recheck for the DTC when the following conditions are met:

NOTICE:
If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because DTC may be stored after the A/C has been operating for a while.

HINT
* When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from 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, 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, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant. In this case, to complete the repair, it is necessary to replace the cooler dryer.

Result:

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

16. REPLACE EXPANSION VALVE

(a) Replace the expansion valve with a new or a known good one Disassembly.

HINT
Replace the expansion valve with a new or a known good 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 FOR DTC

(a) Recheck for the DTC when the following conditions are met:

NOTICE:
If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while.

HINT
* When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from 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 new or a known good one, the condenser or pipes may be clogged with dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes.

Result:

B -- REPLACE CONDENSER Removal

A -- END

19. REPLACE A/C PRESSURE SENSOR

(a) Replace the A/C pressure sensor Removal.

HINT
Since the A/C pressure sensor cannot be inspected while it is removed from the vehicle, replace the A/C pressure sensor with a new or a known good one and check that the condition returns to normal.

NEXT -- Continue to next step.

20. RECHECK FOR DTC

(a) Recheck for the DTC when the following conditions are met:

B -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

A -- END