Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
The cost to diagnose the B12A9 MERCURY code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
Under normal operation, the air inlet door actuator motors are supplied voltage or ground on the circuit, depending on desired actuator rotation, by the Electronic Manual Temperature Control (EMTC) Module or Electronic Automatic Temperature Control (EATC) Module. The EMTC module or EATC module then supplies the appropriate voltage or ground to the other side of the actuator motor on. The module sets the OBDII code when the Air Inlet Door Actuator is not to factory specifications.
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