What is a capacitor in an air conditioner?

In an air conditioning system, the capacitor is a cylindrical electrical component that stores electrical charge and releases it to give the compressor and fan motor the initial boost they need to turn on. Without a working capacitor, these motors cannot start even if power reaches them. Most residential units in Tampines use either a run capacitor (which keeps running while the compressor operates) or a start capacitor (which engages only during startup), though some systems have both.

A failed capacitor is one of the most common air conditioning breakdowns. Signs include:

• The outdoor unit runs but the compressor does not, leaving only the fan spinning
• The indoor fan does not turn on at all
• A buzzing or humming sound from the unit without the compressor starting
• Weak cooling or no cooling output

Capacitors typically fail because of age, heat exposure (common in Singapore's tropical climate), voltage spikes, or normal wear over 5 to 10 years of operation. A capacitor that is leaking fluid, has a bulging case, or burns a visible scorch mark requires immediate replacement. If your unit shows these symptoms, contact an air conditioning repair provider to test and replace the component rather than attempting it yourself, as capacitors can retain dangerous electrical charge.