Can a defective fan motor cause a run capacitor to go bad?

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SUMMARY

A defective PSC (Permanent Split Capacitor) fan motor can indeed cause the run capacitor to fail, primarily due to increased current draw from shorted windings. This elevated current leads to higher temperatures within the capacitor, ultimately reducing its lifespan. The failure is typically gradual rather than instantaneous, with the run capacitor being more susceptible to long-term damage from a malfunctioning motor. Understanding the relationship between motor defects and capacitor performance is crucial for effective heat pump maintenance.

PREREQUISITES
  • Understanding of PSC fan motors and their operation in heat pumps
  • Knowledge of run capacitors and their role in motor performance
  • Familiarity with electrical current ratings and their impact on component lifespan
  • Basic principles of electrical schematics related to HVAC systems
NEXT STEPS
  • Research the effects of shorted windings on PSC fan motors
  • Learn about the thermal characteristics of run capacitors
  • Study electrical schematics for heat pump systems
  • Investigate preventive maintenance practices for HVAC components
USEFUL FOR

HVAC technicians, electrical engineers, and anyone involved in the maintenance and repair of heat pump systems will benefit from this discussion.

fourthindiana
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I already have made the thread "Can a defective DRC [Dual Run Capacitor] on a heat pump cause the fan motor to go bad?" Earlier today I told my father how a defective DRC on my heat pump caused the run winding on my fan motor to burn up. My father asked me if a defective fan motor can cause a run capacitor to go bad, which is the reverse of the topic of my other thread. I don't know enough about how capacitors work to deduce the answer to my father's question.

Can a defective PSC fan motor on a heat pump cause the run capacitor for the PSC motor to become defective? If so, how does a defective PSC fan motor on a heat pump cause a run capacitor to become defective?
 
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Do you have a schematic or picture? Usually caps have ratings, so if it is overcharged or shorted it will fail.
 
Last edited:
For a Run capacitor, more likely a shorted motor winding would decrease the capacitor lifetime due to the higher current causing a greater temperature rise in the capacitor. This would be a long-term failure, not instantaneous.

A Start capacitor could be subject to a short-term failure by the same reasoning but with a much higher current.

Cheers,
Tom
 
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