ATC System Test

Possible Causes:

• ATC System Test

Testing

1. Make sure there is vehicle communication with the BCM, the automatic temperature control module and the powertrain control module before proceeding. See COMMUNICATIONS  category. With the scan tool, read engine DTC's. If any climate control related DTC's are present, see DIAGNOSTIC TROUBLE CODE IDENTIFICATION  table.
2. With the scan tool, read body DTC's. If any climate control codes are present, continue with next step. If no codes are present, recalibrate the doors and BCM and recheck system.
3. Record and erase the code(s). Set the temperature control at 75°F (24°C), start the engine and with the scan tool, read DTC's. If no code appears, slowly turn the temperature control from 65-85°F (29.44-18.3°C), then back to 65°F (18.3°C) while observing the scan tool for codes. If a code appears, see DIAGNOSTIC TROUBLE CODE IDENTIFICATION  table.
4. If a code still does not appear, turn the ATC control from 60-90°F (15.56-32.22°C), then back to 60°F (15.56°C). Push each mode button waiting 20 seconds between each one. Upon seeing the first code appear, stop and erase the code and perform the appropriate test.
5. If no codes appear, recalibrate the doors by pressing and holding the floor, mix and defrost buttons at the same time until the display starts to flash. Observe the scan tool for DTC's.
6. When the first code appears, record that code and allow the system to finish calibration. If multiple codes appear, repair any that relate to a short circuit first. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION  table. If a short to battery code is set, all 4 Output Shorted To Battery codes will appear. It will then be necessary to isolate each circuit to determine which is at fault.
7. Erase the DTC(s) and see DIAGNOSTIC TROUBLE CODE IDENTIFICATION  table, for the related symptom of the first code that appeared. If no codes have appeared, recalibrate the doors, reset the BCM and ATC head and recheck the ATC system performance.