OEM Carrier 40VA Control Transformer for Model C48A403561

This OEM replacement control transformer (part# HT01BD236) is the factory-specified unit for the Carrier C48A403561 packaged unit. The transformer steps down line voltage (120V) to the 24V low-voltage signal that powers your thermostat, contactor coil, and all control board functions. When this component fails, the entire control circuit goes dead — your thermostat goes blank, the system won't respond to any calls for heating or cooling, and no error codes will display because there is simply no power to run them.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | Spade terminal connections | Factory-matched impedance for stable control voltage under load
• OEM vs Generic: The OEM HT01BD236 transformer is wound to Carrier's exact VA and voltage tolerance specifications. Generic transformers frequently deliver inconsistent secondary voltage, causing erratic contactor chatter, nuisance lockouts, and premature control board failure — making the OEM choice a smart long-term investment.
• Install difficulty: 2/5 — Always disconnect power at the breaker and verify voltage is absent before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 0V at terminals before touching wiring). Photograph all wire connections before removal and restore power only after all terminals are secured.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our climate-controlled warehouse.

Compatibility: Engineered specifically for the Carrier C48A403561 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or old component label before ordering. Our parts specialists are available to confirm fitment — order with confidence and get your system back online fast. In stock and ships today.