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This OEM replacement transformer (part number HT01CN241) is the factory-specified control circuit transformer for the Carrier FY5BNF042015AAAA fan coil unit. The transformer steps line voltage down from 120V to 24V AC, powering the low-voltage control circuit that connects your thermostat, control board, and safety switches. When the transformer fails, the entire control circuit loses power — symptoms include a completely unresponsive thermostat, a blank control board, or a system that won't start under any condition despite having line power at the unit.
Compatibility: Designed as a direct OEM replacement for the Carrier FY5BNF042015AAAA fan coil unit. Confirm primary voltage (120V) and VA rating on your existing transformer's label before ordering. If your system has a 208V or 240V primary transformer, do not substitute this unit. Our fitment team is available to verify compatibility before you purchase — no guesswork required.