OEM Carrier Control Transformer 40VA 208/240V to 24V — HT01BD209 for Model PY3PNA048115NB

This OEM Carrier control transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PY3PNA048115NB packaged unit. The transformer steps down 208/240V line voltage to the 24V signal voltage that powers your thermostat, contactor coil, and all low-voltage control logic. When this transformer fails, the entire control circuit goes dead — the system won't respond to the thermostat, won't stage heating or cooling, and may blow the low-voltage fuse repeatedly. It is one of the first components to test when a unit shows zero response despite line voltage being present at the disconnect.

• Specs: 208/240V primary input | 24V secondary output | 40VA power rating | 50/60 Hz | OEM part number HT01BD209
• OEM vs Generic: This is the factory-matched OEM transformer engineered to Carrier's exact VA rating and insulation class. Generic aftermarket transformers often ship underrated or with looser winding tolerances, risking repeated blown fuses or premature contactor coil failure.
• Install difficulty: 2/5 — Always disconnect power at the unit disconnect AND the breaker before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (verify 0V before touching wiring). Photograph all wiring connections before removal. Swap primary and secondary leads one at a time to prevent miswiring.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PY3PNA048115NB. Always verify your unit's data plate matches the 208/240V primary and 24V secondary specifications before ordering. Our fitment team is available to confirm compatibility before you purchase — reach out before you order if you have any questions.