OEM Carrier Control Transformer 40VA 208/230V to 24V — HT01BD209 for Model PY3PNA048115AB

This is the genuine OEM Carrier control transformer (part #HT01BD209) factory-specified for the Carrier PY3PNA048115AB packaged unit. The 24V control transformer is the heartbeat of your HVAC system's low-voltage circuit — it steps down 208/230V line voltage to the 24V signal voltage that powers the thermostat, control board, contactor coil, and all safety circuit components. When this transformer fails, the entire control circuit goes dead: the thermostat goes blank, the system will not respond to any calls for heating or cooling, and nothing works. It is one of the most common and straightforward repairs an HVAC technician will make.

• Specs: 40VA capacity | 208/230V primary input | 24V secondary output | 50/60 Hz | OEM part #HT01BD209 | Alternate cross-reference: 4000A46E07AE28 | Replaces: HT01BD207, HT01CN232, 9076-00
• OEM vs Generic: This genuine Carrier OEM transformer is wound to exact factory VA and voltage tolerances, ensuring the control board and low-voltage components receive stable, clean 24V power. Generic transformers can exhibit voltage sag under load, causing intermittent lockouts, nuisance tripping of the thermal fuse, and premature control board failure.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after install). Photograph all low-voltage wiring connections before removing the old transformer. Note the wire colors on both primary (line) and secondary (24V) terminals.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our warehouse when ordered before 3PM local time.

Compatibility: Factory-matched replacement for Carrier model PY3PNA048115AB packaged units. This part also fits other Carrier, Bryant, and Payne systems originally specifying the HT01BD209 or its predecessor part numbers — always verify your unit's data plate voltage requirements before ordering. Have questions about fitment? Our HVAC parts team confirms compatibility before you buy.