OEM Carrier Transformer 40VA 120V/24V for Model C50A202551

This OEM control circuit transformer (part number HT01BD236) is the factory-specified replacement for the Carrier C50A202551 commercial packaged rooftop unit. The transformer steps down 120V line voltage to the 24V signal required by your thermostat, contactor coils, gas valve, and control board. When this component fails, the entire control circuit loses power — nothing responds, the thermostat goes blank, and the system will not attempt to heat or cool under any call. It is often the first component to inspect when a unit appears completely dead despite line voltage being confirmed at the unit.

• Specs: 40VA rated | 120V primary input | 24V secondary output | Class 2 transformer | OEM part number HT01BD236 | Factory-matched to C50A202551 control circuit requirements
• OEM vs Generic: OEM transformers are wound and insulated to exact Carrier factory specifications, ensuring stable 24V output under full load. Generic alternatives may sag under peak demand, causing intermittent lockouts, nuisance tripping, or premature contactor coil failure.
• Install difficulty: 2/5 — Shut off all power at the disconnect and verify with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, wire nuts or spade connectors, multimeter. Photograph all wiring connections before disconnecting the old transformer to ensure correct reinstallation.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. Ships same business day from our NationalHVACParts.com warehouse.

Compatibility: Designed for the Carrier C50A202551 commercial rooftop packaged unit. Always verify your existing transformer's VA rating and primary/secondary voltages on the data plate before ordering to confirm fitment. Our parts specialists are available to verify compatibility before you purchase — no guesswork required.