STEP 1. Using scan tool MB991958, check for diagnostic trouble code.
Check if an A/C control panel 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.
Is the DTC set?
Refer to DIAGNOSTIC TROUBLE CODE CHART . Go to Step 2.
STEP 2. Check air mixing damper control motor connector C-214 and A/C control panel connector C-232 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
STEP 3. Check the wiring harness between A/C control panel connector C-232 (terminals 28, 32, 30, 31 and 29) and air mixing damper control motor connector C-214 (terminals 3, 6, 2, 5 and 1).