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This OEM control transformer (part# HT01CN236) is the factory-specified replacement for the Carrier FB4ANF048008AFAA air handler. The transformer steps down 120V line voltage to the 24V signal required by the thermostat, control board, contactor coil, and all low-voltage control circuits. When it fails, the thermostat goes completely dark, the system makes no response to any call for heating or cooling, and downstream 24V components receive no power — making it one of the most impactful single-component failures in the system.
Compatibility: Engineered as a direct OEM replacement for the Carrier FB4ANF048008AFAA air handler. Always verify primary voltage on your unit's data plate matches 120V before ordering. If your system runs on 208/240V primary, do not install this unit. Our fitment team is available to confirm compatibility before you order — same-day shipping ensures you're back up and running fast.