OEM Carrier Transformer 40VA 120V to 24V for Model C4850C48ZN050500

This OEM control circuit transformer (part number HT01BD236) is the factory-specified replacement for the Carrier C4850C48ZN050500 packaged unit. The transformer steps line voltage (120V) down to the 24V signal voltage that powers your thermostat, contactor coil, and all control board logic. When it fails, the entire control circuit goes dead — the thermostat goes blank, the unit won't respond to any calls for heating or cooling, and no fault codes are generated because the board itself has no power. A failed transformer is often misdiagnosed as a control board failure, so always verify 24V output at the transformer secondary before replacing more expensive components.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | OEM part number HT01BD236 | Direct factory replacement with matched impedance and thermal protection
• OEM vs Generic: OEM transformers include factory-matched VA ratings and built-in thermal protection fuses. Generic units frequently lack proper overload protection, risking secondary failures and possible board damage during a short circuit event.
• Install Difficulty: 2/5 — Disconnect power at the breaker and verify zero voltage with a multimeter before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Label all wiring before disconnecting and confirm primary/secondary terminals against the wiring diagram on the unit door.
• Warranty: 1-year OEM factory warranty included. Ships same business day from our climate-controlled warehouse.

Compatibility: Designed specifically for the Carrier C4850C48ZN050500 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. Our fitment team is available to confirm compatibility before you buy — don't guess on a control circuit component. Order today and get same-day shipping on all in-stock OEM parts.