OEM Carrier 40VA Control Transformer for Model C4850C50AK02551

This OEM step-down transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C50AK02551 packaged unit. The transformer converts 120V line voltage to the 24V signal that powers the entire control circuit — including the thermostat, contactor coil, gas valve, and control board. When it fails, the system goes completely silent: the thermostat goes blank, no components respond, and no error codes appear because the control circuit itself has lost power. A failed transformer is often misdiagnosed as a thermostat or control board failure, making correct identification critical before replacing more expensive parts.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | OEM part number HT01BD236 | Factory-matched for Carrier C4850C50AK02551 packaged units
• OEM vs Generic: This OEM transformer meets Carrier's exact VA rating and insulation class. Undersized or off-spec generic transformers can overheat and fail prematurely — or worse, damage the control board by delivering unstable voltage under load.
• Install difficulty: 2/5 — Disconnect power at the disconnect box before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output post-install), wire nuts or spade terminals. Label all wires before disconnecting the old unit and verify polarity on reinstall.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed and factory-matched for the Carrier C4850C50AK02551 packaged unit. Always verify your unit's data plate and existing transformer VA/voltage ratings before ordering to ensure a correct fit. Our team is available to confirm compatibility before you buy — no guesswork required.