OEM Carrier 40VA Control Transformer for Model C4850C50Z2055200

This OEM control transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C50Z2055200 packaged unit. The transformer steps down 120V line voltage to the 24V signal voltage that powers your thermostat, control board, and all low-voltage switching circuits. When the transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system will not respond to any calls for heating or cooling, and in many cases the unit appears completely unresponsive. A failed transformer is often misdiagnosed as a bad control board, making this an important first diagnostic check.

• Specs: 40VA rating | 120V primary / 24V secondary | Hardwired terminations | Factory-matched impedance and insulation class for full compatibility
• OEM vs Generic: OEM transformers (HT01BD236) are wound and insulated to Carrier's exact specifications, providing stable 24V output under variable load. Generic units frequently sag under full control circuit load, causing erratic board behavior and nuisance lockouts.
• Install difficulty: 2/5 — Disconnect power at the breaker and verify zero voltage before starting. Tools needed: flathead and Phillips screwdrivers, multimeter, wire stripper. Label or photograph all low-voltage wiring before disconnecting. Confirm polarity on secondary terminals when reconnecting.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for the Carrier C4850C50Z2055200 packaged unit. Always verify your existing transformer's VA rating and primary/secondary voltage from the unit's data plate before ordering to ensure a correct match. Have questions about fitment? Our HVAC parts specialists verify compatibility before you buy — reach out before placing your order.