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The Goodman B1789882 piston kit is the genuine OEM refrigerant metering device for the GSC130484AC 4-ton 13 SEER air conditioner condenser. The piston (fixed-orifice flow control) meters liquid refrigerant into the evaporator at the precise rate the system was engineered for, ensuring correct superheat, full capacity, and rated efficiency. An incorrectly sized orifice causes flooding, starving, or poor SEER performance.
The OEM Goodman piston is bored to the exact diameter (.0xx") specified for this tonnage, so the system charges and performs as designed. Generic universal piston kits require you to identify and select the correct orifice yourself — choose wrong and you'll chase charge and capacity problems. The OEM kit removes that guesswork.
Advanced — Replacement requires recovering the refrigerant, opening the liquid-line connection, swapping the piston, leak-checking, evacuating, and recharging to spec. This is an EPA Section 608 certified job. Have a licensed HVAC technician perform the work.