It is the actuator tests within the HVAC control module which are key to a speedy diagnosis in this case. Using the actuator tests and the lab scope together enables you to visually see the electronic signal from the HVAC control module to the blower motor resistor, this helps to confirm the fault is with the blower motor.
2010 BMW 520 2.0 Diesel
801207, Replaced HVAC Blower Motor Resistor Module, HVAC Blower Motor
The customer states the HVAC blower is not functional.
Connected a scan tool and found code 801207 – Blower Output Stage: Open Circuit Detected In Load Circuit. With the key on, engine off commanded the HVAC blower motor on using the HVAC control module. Found that the HVAC blower motor did not operate. Removed the glove box and lower trim to gain access to the HVAC blower motor and HVAC blower motor resistor module. Key on, engine off used a multi-meter to check for power and ground at the HVAC blower motor resistor module. Found that power and ground was present. Connected a lab scope to the HVAC blower motor resistor module control wire. Commanded the HVAC blower motor resistor module from the HVAC control module and found that control was present. Removed the HVAC blower motor from the vehicle and found that it was seized. The HVAC blower motor resistor module is integrated with the HVAC blower motor and needs to be replaced as a complete unit. These tests verified that the HVAC blower motor resistor module and HVAC blower motor was faulty.
Replaced the HVAC blower motor resistor module and HVAC blower motor, cleared codes, performed a road test and verified the vehicle operated properly.
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