OEM Carrier Control Transformer 40VA 120V/24V for Model C50A303551

This OEM control circuit transformer (part number HT01BD236) is the factory-specified replacement for the Carrier C50A303551 commercial packaged unit. The transformer steps down line voltage from 120V to 24V AC to power the low-voltage control circuit — including your thermostat, contactor coil, and control board. When it fails, the entire control circuit goes dead: the thermostat goes blank, the system won't respond to any calls for heating or cooling, and no fault codes will display. It is often the first component to suspect when nothing in the system responds.

• Specs: Primary voltage: 120V AC | Secondary voltage: 24V AC | VA rating: 40VA | OEM part number: HT01BD236 | Factory-matched output for Carrier C50A303551 control circuits
• OEM vs Generic: This OEM transformer is wound to exact factory tolerances, ensuring stable 24V output under full load. Generic transformers often deliver inconsistent voltage under load, causing nuisance lockouts, erratic thermostat behavior, and premature contactor coil failure.
• Install difficulty: 2/5 — Disconnect all power before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or terminal connectors. Verify primary and secondary voltage with a multimeter before energizing. Always label or photograph wiring prior to removal.
• Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier C50A303551 commercial rooftop/packaged unit. Verify your existing transformer's primary voltage (120V), secondary voltage (24V), and VA rating (40VA) against your unit's data plate before ordering. If your system is completely unresponsive with no blown fuses, the transformer is the most common cause. Our team is available to confirm fitment before you order — same-day shipping available on all in-stock parts.