Code No. B1079: A/C Refrigerant leaks: Diagnosis

Required Special Tool: 

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A

1. STEP 1. Check the condenser assembly 

   Check that the condenser assembly is not wet.

   Q: Is the check result normal? 

   1. YES:  Go to Step 2.
   2. NO:  Wait until the condenser is dry, and check that no diagnostic trouble code is stored.
2. STEP 2. Using scan tool (M.U.T.-III), diagnose the CAN bus line 
   CAUTION: To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
   1. Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)
   2. Turn the ignition switch to the "ON" position.
   3. Diagnose the CAN bus line.
   4. Turn the ignition switch to the "LOCK" (OFF) position.

   Q: Is the CAN bus line found to be normal? 

   1. YES:  Go to Step 3.
   2. NO:  Repair the CAN bus line (Refer to DIAGNOSIS ).
3. STEP 3. Using scan tool (M.U.T.-III), read the ETACS diagnostic trouble code. 

   Check that the diagnostic trouble code related to the heater controller assembly (A/C-ECU) is not stored.

   Q: Is the diagnostic trouble code stored? 

   1. YES:  Carry out the diagnostic trouble code procedures. Refer to DIAGNOSTIC TROUBLE CODE CHART  .
   2. NO:  Go to Step 4.
4. STEP 4. Using scan tool (M.U.T.-III), check data list. 

   Check that the following service data display contents are normal. (Refer to DATA LIST REFERENCE TABLE  )

   Item No.19: Ambient temperature sensor

   Q: Is the check result normal? 

   1. YES:  Go to Step 5.
   2. NO:  Refer to INSPECTION PROCEDURE 5: AMBIENT TEMPERATURE SENSOR SYSTEM  .
5. STEP 5. Check the A/C pressure sensor 

   Refer to SIMPLE INSPECTION OF THE A/C PRESSURE SENSOR  .

   Q: Is the check result normal? 

   1. YES:  Go to Step 6.
   2. NO:  Replace the A/C pressure sensor.
6. STEP 6. Refrigerant level check 

   Refer to REFRIGERANT LEVEL CHECK, DRAINING AND CHARGING  .

   Q: Is the check result normal? 

   1. YES:  Go to Step 7.
   2. NO:  Correct the refrigerant level.
7. STEP 7. Check whether the diagnostic trouble code is stored again. 

   Q: Is the diagnostic trouble code stored? 

   1. YES:  Refer to INSPECTION PROCEDURE 11: HEATER CONTROLLER ASSEMBLY (A/C-ECU) POWER SUPPLY SYSTEM  .
   2. NO:  The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).