Low Idle With A/C On (Econoline 4.6L, 5.4L & 6.8L)

Check ACCS PID. Connect scan tool to Data Link Connector (DLC). Start engine and allow to idle. Using scan tool, access ACCS PID from PID/DATA MONITOR & RECORD menu. With A/C clutch engaged, ACCS PID value should indicate ON. On models where PCM cannot control A/C clutch on and off, PCM uses ACCS circuit to determine additional load on engine. If ACCS PID does not indicates ON, go to TEST KM, step 10)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV article.