OEM Carrier 40VA Control Transformer HT01BD236 for Model C48A303551

This is the OEM factory-replacement control transformer (part number HT01BD236) for the Carrier C48A303551 packaged unit. The transformer steps down line voltage (120V) to the 24V AC signal that powers your thermostat, contactor coil, and control board. When this component fails, the entire control circuit goes dead — the thermostat goes blank, the system refuses to heat or cool, and no error codes appear because there is no power to generate them. It is frequently the first component to check when a unit appears completely unresponsive.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V AC | OEM part number HT01BD236 | Factory-matched construction for drop-in replacement
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact VA and voltage tolerances. Undersized or off-tolerance generic transformers can overheat under full control-circuit load, tripping the internal fuse and damaging downstream boards — always match the OEM spec.
• Install difficulty: 2/5 — Disconnect all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (verify 0V before touching wiring). Label or photograph all wiring connections prior to removal. The transformer mounts to the control panel with one or two screws and uses push-on or screw-terminal connections.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier C48A303551 packaged unit. Verify your existing transformer's primary voltage, secondary voltage, and VA rating against your unit's data plate before ordering. If your system uses a 208/240V primary input, do not substitute this part — contact our fitment team for the correct transformer. Questions about compatibility? Our HVAC parts specialists verify fitment before every order.