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This OEM replacement transformer (part# HT01CN241) is the factory-specified control circuit transformer for the Carrier FC4DNB048000AAAA fan coil unit. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, and all low-voltage switching components. When it fails, the entire control circuit goes dark — the thermostat displays nothing, the system won't respond to calls for heating or cooling, and the unit sits completely inoperative despite line power being present.
Compatibility: Designed and factory-matched for the Carrier FC4DNB048000AAAA fan coil unit. Always verify your existing transformer's primary/secondary voltage and VA rating on the unit data plate or old transformer label before ordering to confirm fitment. Our HVAC parts specialists are available to verify compatibility before you purchase — no guesswork required.