Test H: ATC System Check

Ensure communication exists between Automatic Temperature Control (ATC), Body Control Module (BCM) and Powertrain Control Module (PCM). If communication exists between modules, go to next step. If communication between modules does not exist, diagnose and repair concern with module communications network. See BODY CONTROL MODULES - CONCORDE, INTREPID, LHS & 300M article in ACCESSORIES & EQUIPMENT.
Using scan tool, read and record PCM DTCs. If any ATC system related PCM DTCs are stored, go to appropriate procedure for ATC system related codes present. See DTC/FAULT MESSAGE DIAGNOSTIC TESTS table. For a complete listing of PCM DTCs, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no ATC system related codes are present in PCM, go to next step.
Using scan tool, read and record BCM DTCs. If any ATC system related BCM DTCs are present, go to appropriate procedure for ATC system related codes present. See DTC/FAULT MESSAGE DIAGNOSTIC TESTS table. For other BCM DTCs present, see appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If no ATC system related codes are present in BCM, go to next step.
If no ATC system related codes were present in PCM or BCM, perform calibration test of A/C-heater housing actuator doors. See ACTUATOR DOOR CALIBRATION under ADJUSTMENTS. After calibration, check ATC system functions and operation. Go to next step.
Review PCM and/or BCM DTCs recorded, then erase DTCs recorded. See CLEARING DIAGNOSTIC TROUBLE CODES in SELF-DIAGNOSTICS. Go to next step.
Set ATC control panel to Fahrenheit (F) scale, and temperature setting to 75°F. Start engine. Monitor scan tool ATC system related DTCs or fault messages. While monitoring scan tool, slowly reduce temperature setting to 65°F. Then slowly increase temperature setting from 65°F to 85°F, then from 85°F to 65°F. If DTCs or fault messages appear, go to appropriate procedure for each DTC or fault message present. See DTC/FAULT MESSAGE DIAGNOSTIC TESTS table. If no DTCs or fault messages appear on scan tool, go to next step.
If no codes are present, set ATC control panel to 60°F. Then, change temperature setting from 60°F (full cold) to 90°F (full heat), then back to 60°F. While monitoring scan tool for first code to set, push any ATC control panel button switch. Wait 20 seconds. Check for ATC DTCs to appear. Then repeat for each button switch of ATC control panel, waiting 20 seconds between each button switch. If ATC DTCs appear, stop, erase ATC DTCs and perform appropriate procedure for ATC DTCs displayed. See DTC/FAULT MESSAGE DIAGNOSTIC TESTS table. If no ATC DTCs were displayed, go to next step.
While monitoring scan tool for DTCs, push floor, mix and defrost buttons at the same time until ATC control panel begins to flash. When flashing begins, ATC system is performing calibration test of A/C-heater housing actuator doors and diagnostic check for ATC DTCs. If no ATC DTC appears, ATC system check is complete. If ATC DTCs are displayed, record first ATC DTC that appears. Record all additional DTCs that appear on scan tool display, and allow system to complete calibration test. Go to next step.
NOTE: If multiple codes appear, repair any DTCs or fault messages for short circuit related condition first. If short to battery voltage DTCs or fault messages appears, all other short to battery DTCs or fault messages will appear. If this occurs, it will be necessary to isolate each circuit to determine which is at fault. See WIRING DIAGRAMS .
Erase all DTCs or fault messages recorded during calibration test. See CLEARING DIAGNOSTIC TROUBLE CODES in SELF-DIAGNOSTICS. Then perform appropriate test procedure for first DTC or fault message which appeared in previous test step. Ensure Automatic Temperature Control (ATC) system and functions are operating properly.