OEM Carrier Control Transformer 120V–24V 40VA for Model PY3PNA024040AB

This OEM replacement control transformer (part number HT01BD209) is the factory-specified unit for the Carrier PY3PNA024040AB system. The transformer steps down line voltage (120V) to the 24V signal voltage that powers your thermostat, control board, and all low-voltage control circuits. When this part fails, the entire control system goes dark — the thermostat loses power, the system will not respond to any calls for heating or cooling, and no fault codes will display on the board.

• Specs: Primary voltage: 120V AC | Secondary voltage: 24V AC | VA rating: 40VA | OEM part number: HT01BD209 | Factory-matched construction for Carrier PY3PNA024040AB
• OEM vs Generic: This is the genuine Carrier OEM transformer, wound to exact VA and voltage specifications. Generic aftermarket transformers often have looser voltage regulation and lower-quality insulation, risking repeated control board failures or nuisance tripping.
• Install difficulty: 2/5 — Always disconnect power at the breaker before servicing. Tools needed: flat-head and Phillips screwdrivers, needle-nose pliers, multimeter to verify 24V output after installation. Photograph all wiring connections before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for Carrier model PY3PNA024040AB. Verify your existing transformer's primary/secondary voltage and VA rating on its label before ordering to confirm fitment. Our parts specialists are available to verify compatibility before you buy — order with confidence and get it shipped today.