Variable Speed ECM Blower Motor Failure Following ERCOT Voltage Spike in Sorento Pflugerville

Kenneth_T_Sorento Homeowner

Posted in Pflugerville Homeowner Forum • Travis County

Question: Following a sudden thunderstorm and power flicker near Lake Pflugerville, our outdoor AC condenser runs outside but zero air blows from indoor vents. The indoor air handler is completely silent and smells slightly like burned electronics. What failed?

✓ VERIFIED PRACTIONER DIAGNOSIS

Travis_H_EPA_Universal Texas TDLR Senior Diagnostics Tech

Texas Department of Licensing & Regulation Certified

A voltage surge following grid re-energization ruptured the inrush thermistor inside the ECM motor end-bell electronic control module, cutting DC power to the brushless motor windings.

Diagnostic Procedure & Field Restoration:

Confirmed 240V high voltage and 24V PWM control signals present at the air handler terminal board.
Removed ECM motor control module and discovered burned thermistor (SG348) with carbon scoring on circuit trace.
Winding resistance test confirmed the motor stator was unharmed (all 3 phase-to-phase readings measured balanced 6.8 Ohms).
Replaced the ECM electronic control module and installed an HVAC whole-system surge protector (Type 2 SPD), restoring full modulating airflow.

Experiencing this exact symptom in Pflugerville?

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