Replacing a Capacitor – Part 1

by Ron Walker

The goal of our HVAC Repair Guide is help educate our St. Augustine customers. This education will help you with more awareness when hiring air conditioning repair contractors. DO NOT attempt these repairs yourself… if you do, you do so at your own risk!

Once again, this HVAC Repair Guide is for educational purposes only!

Safety First!AC Capacitor

Description: The repair explained here is for a Lennox residential heat pump system.  It is nearly identical for any heat pump or air conditioner. All residential HVAC systems have capacitors, most modern day systems have what is called a dual capacitor.  A capacitor helps the compressor and condenser fan motor to run.  This is probably the most commonly failed part on an air conditioner. I’ll have half a 5 gallon bucket filled every week in the middle of summer.

Symptoms:  When a dual capacitor fails, either the outdoor fan will not run, the compressor will not run, or both.  Most often, the outdoor fan will not be running and you will hear the compressor hum, then shut off, hum, then shut off.  Either way, turn the circuit breaker off.

When this repair is needed:  Either the capacitor has failed or its values vary more than 10% from specification.

Prevention:  Your HVAC technician should be checking your capacitors’ values at every maintenance visit.  If the values are not within their specifications, it should be replaced.  The consequences of not replacing a failing capacitor are:

  • Premature compressor and/or condenser fan motor failure
  • Higher electric bills
  • The inconvenience and expense on of a broken air conditioner in the middle of summer
Repair cost:  $100.00 and $350.00 depending whether the replacement is done during a maintenance visit (preventive) or if it breaks down on the weekend or holiday.
Tools Required:
1/4″ or 5/8″ nut driver

Needle nose pliers

Gloves – not required

Voltmeter – not required but highly recommended

In Replacing a Capacitor Part 2, we’ll go through the steps you HVAC Tech will go through.