OEM Carrier 40VA Control Transformer for Model C4850C48AY03061

This OEM step-down transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C48AY03061 packaged unit. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, and all low-voltage switching circuits. When this component fails, the entire control circuit goes dead — the thermostat goes blank, the system refuses to respond to any call for heating or cooling, and no diagnostic codes are generated because the board itself has no power to run.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Class 2 low-voltage output | OEM part number HT01BD236 | Factory-matched for Carrier packaged unit electrical specifications
• OEM vs Generic: The OEM HT01BD236 transformer is wound to exact VA and voltage tolerances required by the Carrier control board. Undersized or off-tolerance generic transformers can sag under load, causing intermittent lockouts, nuisance tripping, or premature control board failure — costing far more in the long run.
• Install difficulty: 2/5 — Disconnect power at the disconnect box and verify zero voltage with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter, wire nuts or spade connectors. Photograph all wiring connections before removal. The transformer typically mounts inside the control compartment with two to four screws.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. In-stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier C4850C48AY03061 packaged unit. Always verify the 40VA rating and 120V/24V primary-to-secondary voltage against the data plate inside your unit's control compartment before ordering. If you are unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you purchase — same-day shipping available on all in-stock orders.