1. Turn ignition switch to OFF position. Place A/C-heater control panel blower switch and temperature selector at mid-range settings. While holding down both the AUTO switch and defrost switch at control panel, start engine. See Fig. 1. Continue to hold switches down until A/C switch LED indicator begins to flash (within 10 seconds), then release switches. Monitor and identify A/C switch LED flashing sequence through a series of indicator flashes (1-9), followed by a 3 second pause, then sequence will repeat.
2. A normal indicator flash consists of a.5 second on, .5 second off pulse. Each indicator flash represents a circuit monitored by automatic A/C control unit. A normal pattern (with no current DTCs present) consists of 9 indicator flashes, then pause for 3 seconds before repeating. A fault indicator is identified by 3 rapid flashes in the place of a normal indicator flash. See Fig. 3.
3. Monitor current DTC display patterns of 9 indicator flashes. Check if any fault indicators are present during display pattern. If any fault indicator(s) are displayed, verify which indicator (1-9) is displaying a current DTC. See Fig. 4.
See CURRENT FAULT INDICATOR IDENTIFICATION table.
Go to appropriate procedure for faulty circuit identified.
If current DTCs are not displayed, check for any history DTCs stored. See HISTORY DTCS.
1. Check for current DTCs. See CURRENT DTCS. Diagnose and repair any current DTCs, if set. If no current DTC fault indicator is present, go to next step.
2. To enter history DTC display pattern, depress A/C switch once. Monitor flashing A/C switch LED display pattern through a series of 5 indicator flashes, pause for 3 seconds, then repeat. Check for history DTC fault indicators (3 rapid flashes) during display pattern of
indicators (1-5). See Fig. 3. If any history DTC fault indicators are present, determine which circuit is at fault. See Fig. 5. Go to appropriate procedure for faulty circuit identified. If no history DTC fault indicators are present, turn ignition switch to OFF position. Turning ignition switch to OFF position during this procedure will terminate self-diagnostics function.