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This OEM control transformer (part number HT01CN241) is the factory-specified replacement for the Carrier FB4BNF024010AAAA fan coil air handler. The transformer steps down incoming 120V line voltage to the 24V AC signal that powers your thermostat, control board, and all low-voltage control circuits. When the transformer fails — due to a shorted control board, wiring fault, or age — absolutely nothing in the system responds: the thermostat goes blank, the air handler won't start, and the condenser locks out. Replacing the transformer is often the first diagnostic step when an otherwise-healthy system goes completely unresponsive.
Compatibility: This transformer is engineered specifically for the Carrier FB4BNF024010AAAA fan coil air handler. Confirm the 40VA, 120V/24V specification on your unit's wiring diagram or data plate before ordering. If you're unsure of fitment, our HVAC parts specialists can verify compatibility before you purchase — no guesswork required. In stock and ready to ship today.