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This is the factory OEM replacement control transformer (part# HT01CN241) for the Carrier FB4BNF036015AAAA fan coil air handler. The transformer steps down 120V line voltage to 24V AC to power the low-voltage control circuit — including the thermostat, contactor coil, and control board. When it fails, the entire control system goes dark: the thermostat shows no power, the system will not respond to any calls for heating or cooling, and you may detect a burning smell or a tripped fuse on the control board.
Compatibility: Designed specifically for the Carrier FB4BNF036015AAAA fan coil air handler. Verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate before ordering. If you are unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you buy — same-day shipping available on all stocked parts.