OEM Carrier Control Transformer 40VA 120V/24V for Model C4850C48AY04051

This is the genuine OEM replacement control transformer (part number HT01BD236) for the Carrier C4850C48AY04051 packaged unit. The transformer steps down line voltage from 120V to the 24V AC signal that powers your thermostat, control board, contactor coil, and every other low-voltage control circuit in the system. When this transformer fails, the entire control circuit goes dark — the thermostat loses power, the system stops responding to calls for heating or cooling, and no fault codes appear because the board itself has no power to display them.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | OEM part number HT01BD236 | Factory-matched for Carrier C4850C48AY04051 packaged units
• OEM vs Generic: This OEM transformer is wound and rated to Carrier's exact VA and insulation specifications. Undersized or off-tolerance generic transformers can overheat under load, trip internal thermal protection, and cause intermittent control failures — costing more in diagnostic time than you save on the part.
• Install difficulty: 2/5 — Disconnect power at the breaker and confirm voltage is off with a multimeter before starting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire stripper, multimeter. Label or photograph all wiring connections before removal. Reconnect primary (line voltage) wires last.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Engineered as the factory-specified replacement for Carrier C4850C48AY04051 packaged units. Always verify your existing transformer's VA rating and primary/secondary voltages against your unit's data plate before ordering. Our parts specialists are available to confirm fitment — order with confidence and get back up and running today.