B121D MERCURY - Rear HVAC Mode Control Input Circuit Short
B121D MERCURY Possible Causes
- Faulty Rear HVAC Mode Control
- Rear HVAC Mode Control harness is open or shorted
- Rear HVAC Mode Control circuit poor electrical connection
- Faulty Heating, Ventilation, and Air-Conditioning (HVAC) Module
How is the B121D MERCURY code repair?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.
B121D:15 Rear HVAC Mode Control Input Circuit Short to Battery or Open
What is the cost to diagnose the B121D MERCURY code
Labor: 1.0The cost to diagnose the B121D MERCURY code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
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- Engine Light ON (or Service Engine Soon Warning Light)
B121D MERCURY MeaningUnder normal operation, the rear auxiliary control is supplied a 5-volt reference and ground from the Heating, Ventilation, and Air-Conditioning (HVAC) Module. When the auxiliary blower motor speed, airflow mode or temperature control is adjusted, the HVAC module reads the voltage from the rear auxiliary climate controls on the auxiliary blower motor speed, airflow mode, and temperature control feedback circuits to determine the requested setting. The OBDII code sets when the HVAC module senses an open, or short to ground or voltage on the rear auxiliary climate controls temperature input circuit.
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