Pureline Pool Pump Motor Capacitor Compatibility Chart

A capacitor is essentially a small energy-storage device that gives the motor’s windings a powerful electrical “kick” to get spinning from a dead stop. Single-phase AC motors (like virtually all residential pool pump motors) can’t self-start the magnetic fields in the stator windings cancel each other out at rest. The capacitor shifts the electrical phase in the start winding, creating the rotational torque needed to overcome inertia and get the rotor moving.

There are two common types:

• Start capacitor – Provides a high-torque burst at startup, then disconnects once the motor reaches ~75% of running speed (via a centrifugal switch). It’s only in the circuit for a second or two.
• Run capacitor  – Stays in the circuit continuously, improving running efficiency, power factor, and torque stability. Some motors use both.

Without a functioning capacitor, the motor will hum loudly but refuse to spin, or it’ll spin sluggishly, overheat, and trip the thermal overload protector. Running repeatedly in this state burns out the windings quickly a much more expensive fix.

Signs of a Failed Capacitor

• Motor hums but won’t start (most common)
• Motor starts only when you manually spin the shaft
• Motor runs hot and shuts off prematurely
• Visible bulging, leaking, or burn marks on the capacitor body

Where to Find the Specs

1. Read the old capacitor directly – the µF rating, voltage, and sometimes Hz are printed on the side. Even a bulged or leaking capacitor usually has a legible label.
2. Check the motor nameplate – some motors list capacitor specs on the data tag.
3. Look up the motor model number – search the manufacturer’s site (Pentair, Hayward, Century/AO Smith, Leeson) with the motor model for the exact capacitor part number.

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