OEM Carrier 40VA Control Transformer for Model C48A203561

This is the factory OEM replacement transformer (part number HT01BD236) for the Carrier C48A203561 packaged unit. The transformer steps down 120V line voltage to the 24V signal voltage required to power your thermostat, contactor coil, control board, and all low-voltage safety circuits. When the transformer fails, the entire control circuit goes dead — your thermostat goes blank, the system won't respond to any calls for heating or cooling, and nothing operates. A failed transformer is often misdiagnosed as a control board or thermostat failure, making proper identification critical before replacing more expensive components.

• Specs: 40VA rating | 120V primary / 24V secondary | OEM part number HT01BD236 | Factory-matched output voltage for stable low-voltage control circuit performance
• OEM vs Generic: This OEM transformer is wound to exact Carrier factory specifications, ensuring precise 24V output under full VA load. Generic transformers often deliver inconsistent secondary voltage, causing nuisance lockouts, erratic thermostat behavior, and premature contactor coil failure.
• Install difficulty: 2/5 — Shut off all power to the unit before servicing. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter, wire nuts. Confirm 0V at primary terminals before touching any wiring. Photograph all wiring connections before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. In-stock units ship same business day from our climate-controlled warehouse.

Compatibility: Designed as a direct OEM replacement for the Carrier C48A203561 packaged unit. Always verify the transformer's VA rating and primary/secondary voltages on your unit's wiring diagram or data plate before ordering. Our HVAC parts specialists are available to confirm fitment — contact us before you order if you have any questions.