Common HVAC Parts Explained
From contactors to blower motors — a plain-English breakdown of the parts inside every AC system and what each one does.
Whether you're a new homeowner or a tech learning the trade, knowing what each major part does makes diagnosing problems (and ordering replacements) much easier. Here's a quick tour of the most common HVAC parts.
Capacitor
Stores and releases electrical energy to start the compressor and fan motor. Failed capacitors are the #1 cause of an AC that won't start.
Contactor
An electrical switch that sends power to the compressor and condenser fan when the thermostat calls for cooling. Pitted or stuck contactors cause intermittent cooling.
Compressor
The heart of the system. Pumps refrigerant through the unit. Compressor failure is the most expensive AC repair — often worth replacing the whole unit.
Condenser fan motor
Spins the fan on top of your outdoor unit to dissipate heat. A seized fan motor causes the compressor to overheat and shut down.
Blower motor
The indoor fan that pushes cold air through your ducts. Variable-speed (ECM) motors are quieter and more efficient than older PSC motors.
Evaporator coil
The indoor coil where refrigerant absorbs heat from your home's air. Frozen coils usually mean low refrigerant or restricted airflow.
Thermostat
The control center. Smart thermostats add scheduling, remote control, and energy reports — but the wiring must match your system.
Need a specific part for your unit? Browse our catalog or text us a picture of your unit label and we'll match it.
Need the right part?
Browse our catalog or text us a picture of your unit label and we'll match it for you.