What Is a Contactor on an Air Conditioner

The contactor is essentially a type of switch that receives a low voltage signal (24V) from your furnace to power on. … This closing of the circuit allows electricity to power the air conditioner’s fan and compressor motors. Contactors come in generally two different types: single pole and double pole.

How do you know if your contactor is bad?

1. Humming. When your AC is on, it may produce a humming sound – but, it won’t power on. …
2. Chattering. When the contacts are dirty, or the coil has become weak, you may hear the plunger make a chattering sound. …
3. Melting.

What causes a contactor to fail?

Electrical failure – Three different electrical issues can cause contactor failure. The insulation between the coil wires can break down and cause a short. The coil can become grounded through another metal component when the wiring insulation deteriorates. The coil can also become stuck in an open position.