Furnace Blower Motor Capacitor — Signs of Failure and Replacement
Published: July 23, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
Signs of a Bad Capacitor
The blower motor hums but does not start, the motor takes longer to start than normal, the motor runs hot, the capacitor is visibly bulging or leaking oil, or the circuit breaker trips when the motor tries to start. A bulging top on a cylindrical capacitor is a clear sign of failure.
Testing a Capacitor
Turn off power to the furnace. Remove the capacitor (discharge it first by placing a screwdriver across the terminals). Set your multimeter to capacitance mode (microfarads — µF). Measure across the terminals. If the reading is more than 10% below the rated microfarads, the capacitor has failed and needs replacement.
Replacement Cost
Capacitor: $15-50 for the part. Professional replacement including service call: $200-400. Capacitors are standardized — most brands use common sizes. Keep a spare capacitor of the correct size if you are handy. Same-day emergency replacement available.