The average air conditioner has a lot of different components. A common point of failure on most AC units is the capacitor, a small device that plays a big role in your AC’s overall operation. Read on and learn what it does, how it works and what to do when it fails.
How AC Capacitors Work
An air conditioning capacitor looks like an oversized battery, but it doesn’t quite operate the same way. Buried within the outdoor cabinet of your AC unit, the capacitor quietly stores a large amount of energy until its time to turn on the unit. On startup, the capacitor delivers a short, but large jolt of energy – enough to properly start your AC unit.
Why Your AC System Needs One
Your AC system’s compressor and fan motors need plenty of juice on start-up. However, this is often more juice than your home’s electrical system can safely handle. Cue your air conditioning capacitor. The capacitor stores enough energy to jump-start your AC unit into operation.
Think in terms of “long-term storage” for batteries and “short-term storage” for capacitors. Your AC system needs the latter in order to start up and ultimately operate as it should. The capacitor briefly supplies this secondary source of energy when needed and goes back to storing energy when finished.
Different Types of Capacitors
Many AC systems feature more than one capacitor. Some units use a primary “start” capacitor for starting the compressor and fan motors and a smaller, secondary “run” capacitor to keep those motors running during a normal AC cycle.
A few units may even feature “dual capacitors” – think two capacitors in one compact package. These devices deliver the same current and voltage, yet they take up less space than your traditional capacitors.
Diagnosing Capacitor Issues
There are plenty of reasons why your air conditioner capacitor may suddenly fail. Age is often a major factor – most capacitors don’t last beyond 20 years. Exposure to excess heat can cause capacitors to fail sooner.
When it comes to diagnosing a bad capacitor, there are a few telltale signs to look out for:
- AC unit won’t start or takes a long time to start
- AC unit starts, but does not cool properly
- AC unit produces smoke or emits a humming noise during operation
- AC unit uses more energy than normal
What to Do If Your Capacitor Fails
You shouldn’t try to repair or replace a capacitor on your own. Improperly handling a capacitor could lead to serious injury or death due to the high voltage risk. Instead, have one of our trusted HVAC technicians diagnose and fix your air conditioning capacitor issues.
