OEM Carrier Transformer 40VA 120V to 24V for Model C4850C48ZG050200

This is the factory OEM replacement transformer (part number HT01BD236) for the Carrier C4850C48ZG050200 packaged unit. The transformer steps down 120V line voltage to the 24V used by the thermostat, control board, contactor coil, and all low-voltage control circuits. When this transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system won't respond to any call for heating or cooling, and no low-voltage components receive power. It is often misdiagnosed as a failed thermostat or control board before the transformer is tested.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01BD236 | Matches factory footprint and terminal configuration for drop-in replacement
• OEM vs Generic: This OEM transformer is wound to exact factory VA and voltage tolerances, ensuring stable 24V output under full control-circuit load. Generic units frequently under-deliver on VA rating, causing nuisance tripping, erratic board behavior, or premature failure under multi-zone or heat pump loads.
• Install difficulty: 2/5 — Disconnect all power before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade terminals. Test incoming 120V and outgoing 24V with a meter to confirm failure before replacing. Photograph all wiring connections prior to disconnecting.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before cutoff.

Compatibility: Designed for the Carrier C4850C48ZG050200 packaged unit. Verify your existing transformer's primary voltage, secondary voltage, and VA rating against your unit's data plate before ordering. If you are unsure of fitment, our parts specialists can verify compatibility before you complete your purchase — same-day shipping available on all in-stock OEM parts.