AIR CONDITIONING SYSTEM(for Automatic Air Conditioning System with Top-mounted Air Conditioner Pressure Sensor), Diagnostic DTC:B1423

DTC Code DTC Name
B1423 Pressure Sensor Circuit

DESCRIPTION

This DTC is stored if refrigerant pressure on the high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less)*1, (195 kPa (2.0 kgf/cm2, 28 psi) or less)*2 or extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more)*1, (2812 kPa (28.7 kgf/cm2, 408 psi) or more)*2. The air conditioner pressure sensor, which is installed to the high pressure side pipe to detect refrigerant pressure, sends 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 and uses it to control the compressor.


DTC No. Detection Item DTC Detection Condition Trouble Area Memory
B1423 Pressure Sensor Circuit

Any of the following conditions is met:


  • Open in air conditioner pressure sensor circuit (Only when the outside temperature is 5 °C (41°F) or more)

  • Short in air conditioner pressure sensor circuit (Only when the outside temperature is 5 °C (41°F) or more)

  • for HFC-134a (R134a): Refrigerant pressure on high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less) or extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more) (Only when the outside temperature is 5 °C (41°F) or more)

  • for HFO-1234yf (R1234yf): Refrigerant pressure on high pressure side is extremely low (195 kPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (2812 kPa (28.7 kgf/cm2, 408 psi) or more) (Only when the outside temperature is 5 °C (41°F) or more)

  • Air conditioner pressure sensor

  • Harness or connector between air conditioner pressure sensor and air conditioning amplifier assembly

  • Air conditioning amplifier assembly

  • Cooler expansion valve (blocked, stuck)

  • Cooler condenser assembly (blocked, deterioration of cooling capacity due to dirt)

  • Cooler dryer (moisture in the refrigerant cycle cannot be absorbed)

  • Cooling fan system (cooler condenser assembly cannot be cooled down)

  • Air conditioning system (leaks, blocked)

 -
DTC Detection Conditions
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3 Pattern 4
Diagnosis Condition Ignition switch ON ○ ○ ○ ○
Only when the outside temperature is 5 °C (41°F) or more. ○ ○ ○ ○
Malfunction Status Open in air conditioner pressure sensor circuit ○ - - -
Short in air conditioner pressure sensor circuit - ○ - -

for HFC-134a (R134a): Refrigerant pressure on high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi)

 - - ○ -

for HFO-1234yf (R1234yf): Refrigerant pressure on high pressure side is extremely low (195 kPa (2.0 kgf/cm2, 28 psi) or less)

 - - ○ -

for HFC-134a (R134a): Refrigerant pressure on high pressure side is extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more)

 - - - ○

for HFO-1234yf (R1234yf): Refrigerant pressure on high pressure side is extremely high (2812 kPa (28.7 kgf/cm2, 408 psi) or more)

 - - - ○
Detection Time 4 seconds or more 4 seconds or more 4 seconds or more 4 seconds or more
Number of Trips 1 trip 1 trip 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

A001UK8E01
*a Air Conditioner Pressure Sensor
*b Air Conditioning Amplifier Assembly

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. Disconnect the A52 air conditioner pressure sensor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A52-1 (+) - A52-3 (-) Ignition switch ON 4.75 to 5.25 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR) Click here

    OK

  2. INSPECT AIRCONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Reconnect the A52 air conditioner pressure sensor connector.

    2. Remove the air conditioning amplifier assembly with the connectors still connected.

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

      A001VWMC01
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      		 - -
      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      F72-33 (PRE) - Body ground

      Ignition switch ON

      (A/C switch: off)

      		 0.74 to 4.61 V

      Tech Tips

      If the result is not as specified, 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.

      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR) Click here

    OK

  3. INSPECT AIRCONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Measure the voltage when the following conditions are met.

      Measurement Condition:
      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)
      Engine speed 2000 rpm

      Note


      • If refrigerant pressure on the high pressure side becomes extremely high during the inspection (if the voltage exceeds 4.61 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 malfunction may recur after a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the cooler (ambient temp. sensor) thermistor and the No. 1 cooler thermistor (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.

        A001VWMC03
        *a

        Component with harness connected

        (Air Conditioning Amplifier Assembly)

        		 - -
        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        F72-33 (PRE) - Body ground

        Ignition switch ON

        (A/C switch: On)

        		 0.74 to 4.61 V
        Result
        Result Proceed to
        OK (When troubleshooting according to DTC) A
        OK (When troubleshooting according to Problem Symptoms Table) B
        NG C

    A

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

  4. INSPECT COOLING FAN SYSTEM


    1. Check if the cooling fan operates normally.

      for 8NR-FTS: Click here

      for 3ZR-FAE: Click here

      Result
      Result Proceed to
      OK A
      NG (for 8NR-FTS) B
      NG (for 3ZR-FAE) C

    B

    GO TO COOLING FAN SYSTEM Click here

    C

    GO TO COOLING FAN SYSTEM Click here

    A

  5. CHARGE SYSTEM WITH REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant.

      for HFC-134a (R134a): Click here

      for HFO-1234yf (R1234yf): Click here

      Tech Tips

      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.

      Result
      Proceed to
      NEXT

    NEXT

  6. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met.

      Measurement Condition:
      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)
      Engine speed 2000 rpm

      Body Electrical > Air Conditioner > Trouble Codes

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the cooler (ambient temp. sensor) thermistor and the No. 1 cooler thermistor (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 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 work, it indicates that the cooler dryer in the cooler condenser assembly is not able to absorb moisture in the refrigerant cycle. It is necessary to replace the cooler dryer in order to complete the repair.

      Result
      Result Proceed to
      DTC B1423 is output A
      DTC B1423 is not output B

    B

    REPLACE COOLER CONDENSER ASSEMBLY Click here

    A

  7. REPLACE COOLER EXPANSION VALVE


    1. Replace the cooler expansion valve with a new one.

      Click here

      Tech Tips

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

      Result
      Proceed to
      NEXT

    NEXT

  8. CHARGE SYSTEM WITH REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant.

      for HFC-134a (R134a): Click here

      for HFO-1234yf (R1234yf): Click here

      Tech Tips

      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.

      Result
      Proceed to
      NEXT

    NEXT

  9. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met.

      Measurement Condition:
      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)
      Engine speed 2000 rpm

      Body Electrical > Air Conditioner > Trouble Codes

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the cooler (ambient temp. sensor) thermistor and the No. 1 cooler thermistor (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 cooler expansion valve with a new or known good one, the cooler condenser assembly or pipes may be clogged due to dirt, dust or other foreign matter. In this case, clean or replace the cooler condenser assembly or pipes.

      Result
      Result Proceed to
      DTC B1423 is not output A
      DTC B1423 is output B

    A

    END

    B

    CLEAN OR REPLACE COOLER CONDENSER ASSEMBLY

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


    1. Disconnect the A52 air conditioner pressure sensor connector.

    2. Disconnect the F72 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A52-2 (PR) - F72-33 (PRE) Always Below 1 Ω
      A52-2 (PR) or F72-33 (PRE) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. INSPECT FOR AIR CONDITIONING SYSTEM LEAK


    1. Install a manifold gauge set.

    2. Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.

    3. Evacuate the air conditioning system and check that vacuum can be maintained.

      OK
      Vacuum can be maintained in the air conditioning system.

      Tech Tips

      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.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR AIR CONDITIONING SYSTEM LEAK Click here

    OK

  12. CHARGE SYSTEM WITH REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant.

      for HFC-134a (R134a): Click here

      for HFO-1234yf (R1234yf): Click here

      Tech Tips

      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.

      Result
      Proceed to
      NEXT

    NEXT

  13. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met.

      Measurement Condition:
      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)
      Engine speed 2000 rpm

      Body Electrical > Air Conditioner > Trouble Codes

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the cooler (ambient temp. sensor) thermistor and the No. 1 cooler thermistor (evaporator temperature sensor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      Result
      Result Proceed to
      DTC B1423 is output A
      DTC B1423 is not output B

      Note

      If the DTC was stored 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 too much refrigerant when the level was insufficient. Therefore, identify and repair the area where refrigerant leaks from as necessary.


    B

    END

    A

  14. INSPECT AIRCONDITIONER PRESSURE SENSOR


    1. Install a manifold gauge set.

    2. Reconnect the A52 air conditioner pressure sensor connector.

    3. Remove the air conditioning amplifier assembly.

    4. Reconnect the F72 air conditioning amplifier assembly connector.

    5. Turn the ignition switch ON.

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

      A001VWMC04
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      		 - -
      Standard Voltage (for HFC-134a (R134a))
      Tester Connection Condition Specified Condition
      F72-33 (PRE) - F72-32 (SG-2)

      Refrigerant pressure: Normal pressure (less than 3025 kPa (30.8 kgf/cm2, 439 psi) and more than 176 kPa (1.8 kgf/cm2, 26 psi))

      		 0.74 to 4.61 V
      Standard Voltage (for HFO-1234yf (R1234yf))
      Tester Connection Condition Specified Condition
      F72-33 (PRE) -F72-32 (SG-2)

      Refrigerant pressure: Normal pressure (less than 2812 kPa (28.7 kgf/cm2, 408 psi) and more than 195 kPa (2.0 kgf/cm2, 28 psi))

      		 0.74 to 4.61 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE AIRCONDITIONER PRESSURE SENSOR Click here

  15. REPAIR AIR CONDITIONING SYSTEM LEAK


    1. Identify the area where refrigerant leaks from.

      for HFC-134a (R134a): Click here

      for HFO-1234yf (R1234yf): Click here

    2. Repair the identified area of the air conditioning system.

    3. Evacuate the air conditioning system.

      Result
      Result Proceed to
      for HFC-134a (R134a) A
      for HFO-1234yf (R1234yf) B

    A

    CHARGE SYSTEM WITH REFRIGERANT Click here

    B

    CHARGE SYSTEM WITH REFRIGERANT Click here

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


    1. Disconnect the F72 air conditioning amplifier assembly connector.

    2. Disconnect the A52 air conditioner pressure sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A52-1 (+) - F72-34 (S5-3) Always Below 1 Ω
      A52-3 (-) - F72-32 (SG-2) Always Below 1 Ω
      A52-1 (+) or F72-34 (S5-3) - Body ground Always 10 kΩ or higher
      A52-3 (-) or F72-32 (SG-2) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR