OEM Carrier Control Transformer 40VA 120V/24V for Model C4850C50AY02761

This OEM replacement transformer (part number HT01BD236) is the factory-specified control circuit transformer for the Carrier C4850C50AY02761 packaged unit. The transformer steps down line voltage from 120V to 24V to power the low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this transformer fails, the entire control system goes dark: the thermostat becomes unresponsive, the system will not heat or cool, and no components will energize. A failed transformer often presents as a blown fuse on the control board or a tripped secondary circuit.

• Specs: 40VA capacity | Primary: 120V | Secondary: 24V | OEM part number HT01BD236 | Factory-matched output tolerance for stable low-voltage control operation
• OEM vs Generic: This factory OEM transformer is wound to Carrier's exact VA rating and insulation class. Off-brand transformers frequently underperform at rated VA, causing voltage sag that triggers nuisance lockouts and premature control board failure.
• Install difficulty: 2/5 — Always shut off power at the disconnect before servicing. Tools needed: flathead and Phillips screwdrivers, wire nuts or spade connectors, multimeter (to verify 24V output after install). Photograph all wiring connections before removal. Inspect for a shorted load that may have caused the original failure — replacing a transformer without clearing a short will blow the new unit immediately.
• Warranty: 1-year OEM factory warranty against defects. In-stock units ship same business day from our warehouse.

Compatibility: Designed for the Carrier C4850C50AY02761 packaged unit. Verify your existing transformer's primary and secondary voltage ratings plus VA rating on the data plate before ordering. If you are unsure of fitment, our HVAC parts specialists will confirm compatibility before your order ships — same-day shipping available on all in-stock orders placed before 3 PM local time.