Condition: Specify whether it is brand new / unused. Brand / OEM: Carrier (also compatible with Bryant, Payne). Model / Part #: HK42FZ012 (secondary / related #: 1012-943-A). Function / Role: This is an integrated furnace control board that manages system operations: ignition sequencing, blower motor control, safety interlocks, humidifier output, EAC (electronic air cleaner) interface, and more. It acts as the “brain” of the furnace, coordinating sensors, switches, components, and timing. Key Specs / Features (as known). Humidifier output: 24 VAC, up to 0.5 A. EAC output: 115 VAC, up to 1.0 A. Board size: 8″ × 7″ (approximate). Replaces older boards such as HK42FZ00. Used in many Carrier, Bryant, and Payne furnace models. Buyers should verify that their system wiring, sensor connectors, and mounting match the HK42FZ012.