What are the specs for this Piston Kit?

The correct replacement for Goodman model GMP100-4 System — B1789865 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 GMP100-4 System — B1789865.

What symptoms indicate I need a new piston kit?

Common symptoms that indicate you need a new piston kit 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 kit 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 Piston Kit for GMP100-4 System — B1789865

Name: OEM Goodman Piston Kit for GMP100-4 System — B1789865
Brand: Goodman
SKU: GOODMAN-11889
Price: 13.95 USD
Availability: InStock

SKU: GOODMAN-11889 Brand: Goodman

$13.95 $18.95

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Texas CMBL #19328542014

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The Goodman B1789865 Piston Kit is a genuine OEM refrigerant metering device (flowrator/piston) for the Goodman GMP100-4 system. The piston precisely meters refrigerant flow into the evaporator coil, and using the correctly sized OEM orifice is essential for proper superheat, capacity, and efficiency. The wrong piston size directly reduces cooling performance and can damage the compressor.

Specifications

Part Type: Piston / flowrator metering device kit
Function: Meters refrigerant flow to the evaporator coil
Fit: Goodman GMP100-4 and compatible coil assemblies
OEM Part Number: B1789865
Brand: Goodman (genuine OEM)

OEM vs. Generic

The genuine OEM piston is drilled to Goodman's precise orifice diameter for the matched system tonnage and refrigerant charge. Generic or mis-sized pistons cause incorrect superheat, flooding, or starving of the coil. For correct system performance, the OEM-specified piston is strongly recommended.

Installation Difficulty

Advanced (4 of 5). Requires recovering refrigerant, opening the liquid-line connection, replacing the piston in the distributor, and evacuating/recharging the system. EPA Section 608 certification is required — this repair should be performed by a licensed HVAC technician.

Confirm OEM number B1789865 and the correct orifice size for your system tonnage before ordering for your GMP100-4.

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 Piston Kit for GMP10...

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Frequently Asked Questions

Does this Piston Kit fit my Goodman GMP100-4 System — B1789865?

Yes. This is the factory-specified OEM piston kit for the Goodman GMP100-4 System — B1789865. 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 kit on my Goodman GMP100-4 System — B1789865?

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 kit?

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

Is this piston kit 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 kit?

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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