Pressure Sensor Circuit - Air Conditioning System (for Automatic Air Conditioning System)

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

DESCRIPTION

This DTC is output 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, which is installed on the high pressure side pipe to detect refrigerant pressure, outputs a refrigerant pressure signal to the A/C amplifier. The A/C amplifier 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 connector from the A/C pressure sensor.





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

Standard Voltage:





Text in Illustration





NG -- CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - 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:





Text in Illustration





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

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

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

(b) Remove the A/C amplifier with the 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 A/C amplifier, 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 - 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 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 function operates.
* 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 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:





Result:





Text in Illustration





C -- REPLACE AIR CONDITIONING AMPLIFIER Removal

B -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Air Conditioning System (For Automatic Air Conditioning System)
A -- Continue to next step.

5. INSPECT COOLING FAN SYSTEM

(a) Check that the cooling fan operates normally.

HINT
* Component Tests and General Diagnostics for 2AZ-FE.
* Component Tests and General Diagnostics for 2ZR-FE.

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

6. 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 DTCs.

NEXT -- Continue to next step.

7. RECHECK DTC

(a) Recheck for DTCs 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 DTCs. If the DTC is not output after this work, 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 EXPANSION VALVE

A -- REPLACE COOLER DRYER Disassembly

8. REPLACE EXPANSION VALVE

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

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

NEXT -- 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 DTCs 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 the 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 new 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

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

(a) Disconnect the connector from the A/C amplifier.

(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 Removal

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

(a) Disconnect the connector from the A/C amplifier.

(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 Removal

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

(a) Disconnect the connector from the A/C amplifier.

(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.

14. 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.

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.

15. CHARGE REFRIGERANT

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

NEXT -- Continue to next step.

16. RECHECK DTC

(a) Recheck for DTCs 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 the 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 from as necessary.

B -- INSPECT A/C PRESSURE SENSOR

A -- END

17. INSPECT A/C PRESSURE SENSOR

(a) Install the manifold gauge set.

(b) Disconnect the connector from the A/C pressure sensor.

(c) Connect the three 1.5 V dry cell batteries' positive (+) lead to terminal 3, and the negative (-) lead to terminal 1.





(d) Connect the voltmeter's positive (+) lead to terminal 2, and the negative (-) lead to terminal 1.

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

Standard Voltage:





Text in Illustration





NG -- REPLACE A/C PRESSURE SENSOR Removal

OK -- REPLACE AIR CONDITIONING AMPLIFIER Removal

18. 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