What are the specs for this Piston?

The correct replacement for Goodman model WGHP4360AAA — B1789888 is this exact part. It is the factory-specified replacement with exact OEM specifications. Using a part with different specifications can cause equipment damage or void your warranty. You can verify this by checking the data plate on your Goodman equipment which lists the model number WGHP4360AAA — B1789888.

What symptoms indicate I need a new piston?

Common symptoms that indicate you need a new piston include unusual noises, intermittent operation, complete failure to operate, or visible damage. For specific diagnostic guidance, visit nationalhvacparts.com/pages/hvac-diagnostic.

Is this piston compatible with Bryant or Payne systems too?

Many Goodman parts are cross-compatible with Bryant and Payne systems since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across multiple brand labels with different model numbers. To verify cross-compatibility, check your Bryant or Payne equipment service manual for cross-compatible part numbers, or contact info@nationalhvacparts.com with your model number for confirmation.

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Goodman

OEM Goodman Flow Check Piston Kit for WGHP4360AAA — B1789888

Name: OEM Goodman Flow Check Piston Kit for WGHP4360AAA — B1789888
Brand: Goodman
SKU: GOODMAN-903
Price: 10.95 USD
Availability: InStock

SKU: GOODMAN-903 Brand: Goodman

$10.95 $14.78

OEM Guaranteed

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30-Day Returns

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Texas CMBL #19328542014

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Govt POs Accepted

The genuine Goodman B1789888 Flow Check Piston Kit is a factory-original metering device made for the Goodman WGHP4360AAA heat pump. The flow-check piston meters refrigerant into the coil in one direction and allows full flow in the other — essential for proper heat-pump operation in both heating and cooling modes. A correctly sized piston is critical to system capacity and efficiency.

Specifications

OEM Part Number: B1789888
Brand: Goodman
Component Type: Flow Check Piston / Metering Orifice Kit
Designed Fit: WGHP4360AAA heat pump
Function: Bi-directional refrigerant metering
Condition: Brand-new OEM

OEM vs. Generic

This OEM kit is bored to the exact orifice size specified for your unit's tonnage, ensuring proper superheat/subcooling and rated capacity. Installing the wrong-size generic piston causes poor cooling, high head pressure, or compressor strain. Because the bore size is matched to the system, the OEM part removes the guesswork.

Installation Difficulty

Advanced — Professional Only — Installation requires refrigerant recovery, opening the liquid-line fitting to swap the piston and O-ring/seal, re-sealing, evacuating, and recharging. This is EPA Section 608 work and should be handled by a certified HVAC technician.

Shipping Information

Orders placed before 3PM CST ship same business day
Standard delivery: 2-5 business days
Express shipping available at checkout
Free shipping on orders over $75
Tracking number emailed upon shipment

Return Policy

30-day returns on unused parts in original packaging
Electrical parts (capacitors, contactors, control boards) are final sale once installed
Email info@nationalhvacparts.com to initiate a return
Refunds processed within 5-7 business days

OEM Goodman Flow Check Piston Ki...

$10.95

Frequently Asked Questions

Does this Piston fit my Goodman WGHP4360AAA — B1789888?

Yes. This is the factory-specified OEM piston for the Goodman WGHP4360AAA — B1789888. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.

How do I replace the piston on my Goodman WGHP4360AAA — B1789888?

Refer to your equipment service manual for model-specific steps. General approach: turn off power, photograph connections, remove old part, install new part, restore power and test. For gas components, hire a licensed technician. Email info@nationalhvacparts.com for guidance.

What symptoms mean I need a new piston?

Common symptoms: unusual noises, intermittent operation, complete failure, or visible damage. Visit our diagnostic hub for symptom-based troubleshooting.

Is this piston compatible with Bryant or Payne too?

Many Goodman parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.

Should I use OEM or aftermarket for my Goodman piston?

OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.

How fast does National HVAC Parts ship?

Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.

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