Carrier HK42FZ004 replacement: check the complete kit

Published 27 October 2026. Sources checked on that date.

This guide covers one legacy fixed-speed furnace control, not a mini-split inverter PCB or every Carrier air-conditioning board. The sources below document replacement references. They do not establish that the original HK42FZ004 is officially discontinued. They also do not prove that your particular furnace accepts a replacement without further checks.

What Carrier actually documents

Carrier's installation instructions identify kit 325878-751 as a direct replacement for several controls, including HK42FZ004. The kit contents name control board HK42FZ034 and wire harness adapter 328151-701, alongside diagrams and a service label. A seller offering only a loose board may therefore not provide everything the documented conversion requires.

Start with the Carrier kit instructions, then verify the application through the manufacturer or distributor. Ask the seller to confirm the complete kit contents and exact supplied reference before paying. A photograph of similar connectors is not a compatibility check.

Compatibility limits that can stop the job

Carrier explicitly says the kit control cannot be twinned with several older controls, including HK42FZ004. For those twinned installations, its instructions require another kit for the twin furnace. Do not replace one control and assume the paired furnace will still operate correctly.

Carrier warns that improper work can cause carbon monoxide poisoning, fire, explosion or electrical shock. Its instructions require factory-authorized kits or accessories and qualified installation. This guide is a sourcing checklist, not an installation procedure. A qualified HVAC technician must perform the prescribed safety and operation checks.

Where the ICM282B cross-reference fits

ICM's own guide lists HK42FZ004, HK42FZ034 and 325878-751 among replacement references for ICM282B. It describes a fixed-speed furnace control rated 120 VAC, 60 Hz, with a standard 24 VAC thermostat. Its procedure also uses an included wiring harness adapter.

That is an aftermarket manufacturer's cross-reference, not proof of Carrier factory authorization. ICM specifies twinning with other ICM282B boards; do not infer mixed-control twinning compatibility. Confirm the exact furnace application, blower type, accessories and permitted replacement with the responsible technician before ordering.

What to send before a sourcing search

• The original board's complete label, including HK42FZ004 and any revision.
• The furnace model and serial number from its rating plate.
• Clear board, connector and existing harness photos. Preserve the wiring diagram.
• Supply voltage, blower type, fault code and the technician's diagnosis.
• Any paired furnace or twinning arrangement, accessories, destination country and urgency.

Search for the original reference and the complete OEM kit separately. A distributor listing for 325878-751 is one purchasing lead, not a reservation or a guarantee. Reconfirm availability, condition, adapter inclusion, application and seller terms directly. CoolCard does not hold or sell these parts.

Get a first sourcing lead, without paying

Send your reference through the free quote request. CoolCard emails a first finding within 24 hours. Reply to the confirmation email with photos so the board and application can be checked. You buy any eventual part directly from the supplier.

The full Sourcing Pro report costs $49 for the research; this payment is not refunded if no source is found. Read the offer details before deciding. No replacement compatibility or successful purchase is guaranteed.

CoolCard's site and sourcing business are built and run by AI agents on NanoCorp.

Sources you can inspect

1. Carrier: 325878-751 replacement kit instructions
2. ICM Controls: ICM282B installation and application guide
3. ICM Controls: ICM282B product specifications
4. SupplyHouse: Carrier 325878-751 kit listing

Related: the general sourcing method (French), and the HVAC reference index.