Signs of Bad AC Capacitor & How to Replace

By Fix4U Team
Air Conditioners, Appliances

Of all air conditioner electrical components, the run capacitor is one of the most prone to failure. These small cylindrical units use stored voltage to start the compressor and fan motors.

When an AC capacitor goes bad, the entire cooling system grinds to a halt. Learning to identify capacitor problems provides a chance to repair before enduring hot summer days awaiting service. This AC troubleshooting guide from Fix4U Repairs covers diagnosing bad capacitors and replacement tips.

How Does the AC Run Capacitor Work?

The run capacitor has two key roles:

  • Provides the jolt of power needed to get the compressor motor spinning from standstill. The compressor then keeps running from normal current.
  • Runs the blower fan motor at designated speeds to properly circulate air through ductwork.

The capacitor stores enough voltage to briefly start the motors before discharge. Once running, momentum keeps the motors spinning.

Signs of a Failing or Broken AC Capacitor

Fix4U Repairs' Technicians Fixing Bad Ac Capacitors  Problem In Gta

Watch for these common symptoms of a bad capacitor:

  • AC not turning on when thermostat calls for cooling.
  • Tripping breaker or blowing fuse when compressor tries starting.
  • Loud humming sound but compressor won’t start up.
  • Fan blower fails to activate with compressor running.
  • Intermittently working then failing again.
  • Visibly bulging or leaking oil capacitor casing.
  • Lower than normal capacitance reading when tested.
  • High-pitched whining or screeching sound.

What Causes Capacitor Failure?

Common causes of AC capacitor failure include:

  • Age: Eventually capacitor plates wearing out causes reduced capacitance and failure. Lifespan is 5-10 years.
  • Electrical Surges: Power spikes from storms, grid issues, appliance cycling can damage capacitors.
  • Overheating: Heat from nearby components, direct sun exposure, or blocked ventilation can overheat capacitors.
  • Improper Sizing: Capacitors incorrectly sized for compressor or blower motor draw will fail prematurely.
  • Moisture: Water leaking into the capacitor casing can short out contacts and cause failure.
  • Poor Manufacturing: In rare cases, defects from manufacturing like internal short circuits lead to premature capacitor failure.
  • Incorrect Installation: Failure to properly install and connect the capacitor terminals results in rapid failure.

How to Test and Replace a Bad AC Capacitor

Follow these steps to check a capacitor and install a replacement if needed:

  • Disconnect Power: Always turn off the AC breaker or switch and discharge the capacitor before doing work.
  • Remove Wiring & Capacitor: Label wires then disconnect the old capacitor. Note mounting brackets.
  • Test Capacitance: Use a multi-meter to measure microfarads. Compare to original capacitor rating.
  • Get Replacement: Purchase a new capacitor matched to your AC unit with correct microfarads.
  • Install New Capacitor: Insert new capacitor and reconnect wires. Secure tightly in mounting bracket.
  • Restore Power: Turn AC back on and verify compressor and blower now start up properly.

Think your AC capacitor’s bad? Call Now To Fix Your AC!

Signs It’s Time to Call an AC Pro

If you smell burning plastic, see leaking oil, or are unsure of capacitance testing and wiring, it’s best to rely on a professional for capacitor replacement to prevent system damage. The Fix4U Repairs team is ready to quickly diagnose and change out bad AC capacitors. Call us at (647) 363-5205!

Preventing Future AC Capacitor Failures

Routine maintenance helps capacitors last longer:

  • Have an HVAC technician annually test capacitance.
  • Use hardwired surge protectors to avoid electrical damage.
  • Keep the capacitor shaded and clear of water and dust.
  • Arrange for biannual tune-ups to catch issues early.

Enjoy reliable cooling this season – schedule AC maintenance today with the experts at Fix4U Repairs!

(647) 363-5205

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