INSPECTION PROCEDURE 4: Outside/inside air changeover is not possible: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB992006: Extra Fine Probe
• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: V.C.I.
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A

1. STEP 1. Using scan tool MB991958, check for diagnostic trouble code  .
   CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

   Check if an heater controller assembly (A/C-ECU) DTC is set.

   1. Connect scan tool MB991958. Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)  ."
   2. Turn the ignition switch to the "ON" position.
   3. Check if the DTC is set.
   4. Turn the ignition switch to the "LOCK" (OFF) position.

   Q: Is the DTC set? 

   • YES:  Refer to appropriate DTC table:

     Refer to DIAGNOSTIC TROUBLE CODE TABLE - VEHICLES WITHOUT A/C .

     Refer to DIAGNOSTIC TROUBLE CODE TABLE - VEHICLES WITH A/C .

   • NO:  Go to Step 2.
     Fig 1: Connecting Special Tool MB991910 To Data Link Connector

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Check outside/inside air selection damper control motor connector C-109 and heater controller assembly (A/C-ECU) connector C-61 for loose, corroded or damaged terminals, or terminals pushed back in the connector  .

   Q: Are outside/inside air selection damper control motor connector C-109 and heater controller assembly (A/C-ECU) connector C-61 in good condition? 

   • YES:  Go to Step 3.
   • NO:  Repair or replace the connector. Refer to HARNESS CONNECTOR INSPECTION . Check that the A/C works normally.
3. STEP 3. Check the wiring harness between heater controller assembly (A/C-ECU) connector C-61 (terminals 36, 34, 35, 33 and 28) and outside/inside air selection damper control motor connector C-109 (terminals 2, 5, 4, 1 and 3)  .
   • Check the heater controller assembly (A/C-ECU) signal line for open and short circuit.

   Q: Are the wiring harness between heater controller assembly (A/C-ECU) connector C-61 (terminals 36, 34, 35, 33 and 28) and outside/inside air selection damper control motor connector C-109 (terminals 2, 5, 4, 1 and 3) in good condition? 

   • YES:  Go to Step 4.
   • NO:  Repair the wiring harness. Check that the A/C works normally.
4. STEP 4. Replace the outside/inside air selection damper control motor and check the trouble symptom again 

   Check the trouble symptom again.

   Q: Is the check result satisfactory? 

   • YES:  The procedure is complete.
   • NO:  Replace the heater controller assembly (A/C-ECU).