What are common indicators of a failing HVAC blower motor and how is it diagnosed?

• A. Strong airflow regardless of settings and no noise.
• B. Weak or no airflow, unusual noise; check for voltage supply, resistor pack, and replace faulty blower motor or resistor.
• C. Excessively loud airflow with full power and no need for testing.
• D. Replace the blower motor without checking electrical supply.

Answer: (B)

When the HVAC blower motor is failing, you usually see weak or no airflow and you might hear unusual grinding or squealing noises. That combination points to a problem in the motor itself or in the control path (like the blower resistor pack) rather than a simple duct or sensor issue. Diagnosing effectively means confirming the electrical supply to the blower at different fan speeds and inspecting the resistor pack for opens, shorts, or signs of burning. If voltage reaches the motor but it won’t run or only runs on some speeds, the motor or the resistor pack is faulty and should be replaced. In contrast, airflow that is strong at all settings with little to no noise suggests other issues, and replacing the motor without checking the electrical supply risks missing a controllable fault.