HVAC Parts Identification Guide
Identify common HVAC components by name, function, and location in the system.
Compressor
Location: Outdoor unit
Function: Compresses refrigerant gas, raising its pressure and temperature. The "heart" of the refrigeration cycle.
Types: Scroll, reciprocating, rotary, screw, centrifugal
Shop Compressors →Capacitor
Location: Inside electrical panel of outdoor or air handler unit
Function: Stores electrical energy to start and run motors (compressor, condenser fan, blower).
Types: Start capacitor, run capacitor, dual-run capacitor
Shop Capacitors →Contactor
Location: Outdoor unit electrical panel
Function: An electrically-controlled switch that connects power to the compressor and condenser fan motor.
Types: Single-pole, double-pole
Shop Contactors →TXV / Metering Device
Location: Indoor unit, at evaporator inlet
Function: Controls refrigerant flow into the evaporator coil based on superheat.
Types: TXV, EEV (electronic expansion valve), fixed orifice, piston
Shop Valves →Control Board / PCB
Location: Air handler or furnace cabinet
Function: The brain of the HVAC system — controls sequencing, safety lockouts, and communication between components.
Types: Furnace control board, defrost board, inverter board
Shop Control Boards →Filter Drier
Location: Liquid line between condenser and metering device
Function: Removes moisture, acid, and contaminants from the refrigerant circuit. Must be replaced after any system opening.
Types: Liquid line drier, suction line drier, bi-flow drier
Shop Filter Driers →Reversing Valve
Location: Outdoor unit (heat pumps only)
Function: Reverses refrigerant flow to switch between heating and cooling modes in heat pump systems.
Types: 4-way reversing valve (energized in cooling or heating depending on manufacturer)
Shop Reversing Valves →Condensate Pump
Location: Near air handler or indoor unit
Function: Pumps condensate water from the drain pan to a remote drain location when gravity drainage is not possible.
Types: Mini condensate pump, secondary pump, inline pump
Shop Condensate Pumps →Find the Part You Need
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