A worn-out AC capacitor or contactor is one of the most common reasons an air conditioner stops working properly. Both parts are inexpensive to replace, but you’re working with electrical components, so safety comes first. Below, we walk through how to test and replace each one, plus when it’s time to call in an HVAC professional instead of doing it yourself.

Signs Your Capacitor or Contactor Is Failing

Before you start, make sure a capacitor or contactor is actually the issue. Common warning signs include:

  • The outdoor unit hums but the fan doesn’t spin
  • The AC struggles to start or takes several tries to turn on
  • You hear a clicking sound from the outdoor unit that doesn’t lead to startup
  • The system shuts off on its own shortly after starting

If you’re seeing these symptoms, a worn capacitor or a stuck contactor is one of the most common causes.

Tools You’ll Need

  • Replacement capacitor or contactor (matched to your unit’s specs)
  • Insulated screwdriver
  • Needle-nose pliers
  • Multimeter (to test the old part before replacing it)

Turn the Power Off First

With anything related to HVAC equipment, safety should come first. Turn your entire HVAC off so there’s no power going to it. Capacitors can hold an electrical charge even after the power is switched off, so give the unit a few minutes to sit before you touch anything inside it. If you’re not fully comfortable working around electrical components at this point, this is a good place to stop and call a professional instead.

Change Out Start/Run Capacitors

All HVAC systems have an AC component with at least one capacitor. This stores electricity to give the fan motors an extra boost. With this at-home repair, take a picture of the wires before you disconnect anything. You can use this for reference as you work. Install a new capacitor by using needle-nose pliers to remove one wire at a time. Reverse the process as you tackle this type of at-home repair, and make sure the wires are in place.

Replace AC Contactor

This part of your HVAC system is a mechanical relay. It transfers low-voltage power from your thermostat to the compressor and condenser fan. An easy at-home repair fix is to replace this HVAC part, which only costs about $25, with a new one. Finish by unscrewing your existing contactor and removing the wires. Reverse the process to install the new one.

Test Your AC Repairs

Last, see if your at-home repair efforts worked by testing your air conditioner. Turn the power back on and set your HVAC thermostat to AC. Wait for it to start. The compressor should kick in as the condenser fan spins. If everything starts and runs as expected, your at-home repair efforts were successful! But if the fan isn’t spinning, you likely have a worn out fan motor. This is when it’s best to call an HVAC professional.

Call Us Today

As above, there are times when it makes more sense to call an HVAC professional about AC repairs. If this applies to your situation, Ardmore Fresh Air is the trusted local HVAC company to contact. We’ll send an HVAC professional to your home ASAP to restore your comfort and peace of mind.

Call an HVAC professional from our experienced team today to request service.