Goodman B1789871 Flow Check Piston Kit

The Goodman B1789871 is a genuine Goodman flow check piston kit with the M20 designation. The flow check piston is the fixed-orifice metering device used in place of an expansion valve in many Goodman split systems. It sits in the liquid line connection at the indoor coil or the outdoor unit and meters refrigerant through a precisely sized bore, shifting to allow free flow in the opposite direction on heat pump systems. The piston size must match the capacity of the outdoor unit the coil is paired with.

Confirm the required piston size from the outdoor unit's installation instructions or rating plate and match it to part number B1789871 before ordering.