DTC U0424: Invalid Data Received From HVAC Control Module

DTC detecting condition: 

Defective data was transmitted from A/C Control Module.

Trouble symptom: 

Cooperation control of air conditioner does not operate properly.

1. CHECK CAN COMMUNICATION HARNESS  .

   Perform the basic diagnostic procedure to check for fault in CAN communication harness. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE 

   Was the basic diagnostic procedure performed up to step 7?

   Yes  : Go to  2.

   No  : Perform the basic diagnostic procedure. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE 

2. CHECK DTC (OTHER THAN U-CODE)  .

   Check the displayed DTC.

   Is DTC other than U**** displayed? (Current code)

   Yes  : Perform the diagnosis for the displayed DTCs other than U-code.

   No  : Go to  3.

3. CHECK DTC (U-CODE)  .

   Check the displayed DTC.

   Is DTC for the bus off or the data no-receive displayed? (Current code)

   Yes  : Perform the diagnosis for DTCs for the displayed bus off or the data no-receive.

   No  : Go to  4.

4. CHECK DTC  .

   Check the displayed DTC.

   Is DTC U0424 displayed? (Current code)

   Yes  : Go to  5.

   No  : Go to  7.

5. CHECK DTC  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the A/C Control Module connector.
   3. Connect the disconnected connectors.
   4. Turn the ignition switch to ON.
   5. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

   Is DTC U0424 displayed? (Current code)

   Yes  : Go to  6.

   No  : Go to  7.

6. CHECK DTC  .

   Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

   Is DTC U0424 detected in several modules? (Current code)

   Yes  : Replace the A/C Control Module. Ref. to AIR CONDITIONER>CONTROL UNIT

   No  : Replace the module that the DTC has been detected.

7. CHECK HARNESS  .
   1. Shake the harness, and check for poor contact.
   2. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

   Is DTC U0424 displayed? (Current code)

   Yes  : Repair the poor contact of harness, or replace the harness.

   No  : Go to  8.

8. CHECK CONNECTOR  .

   Check the connector used for high speed CAN for poor contact.

   Is there poor contact of connector?

   Yes  : Repair the connector that has poor contact, or replace harness.

   No  : It is possible that temporary poor communication occurs. Delete the DTC.