OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY4GNAA24040AA

This is the genuine OEM Carrier control transformer (part #HT01BD209) factory-specified for the Carrier PY4GNAA24040AA packaged unit. The transformer steps down 208/240V line voltage to the 24V control circuit voltage that powers your thermostat, contactor coil, and every low-voltage component in the system. When this part fails, the result is total loss of control — the thermostat goes dark, the system won't respond to any call for heating or cooling, and the unit sits completely dead despite having full line voltage present. A failed transformer is one of the first things an experienced tech checks in a no-response scenario.

• Specs: 208/240V Primary | 24V Secondary | 40VA Rating | 50/60 Hz | OEM Part # HT01BD209 | Replaces HT01BD207, HT01CN232, 9076-00
• OEM vs Generic: This factory OEM unit is wound to exact Carrier tolerances, ensuring the full 40VA capacity needed to reliably pull in contactors and hold the control circuit stable under load. Generic transformers often run under-rated VA, causing nuisance tripping and premature burnout.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Label all low-voltage wires (R, C, G, Y, W) before disconnecting. Verify 24V output on secondary terminals with a multimeter before closing the unit up.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PY4GNAA24040AA packaged units. Also compatible with Bryant and Payne units sharing the HT01BD209 / HT01BD207 / HT01CN232 transformer specification. Always confirm your unit's control voltage requirement (24V) and VA demand against this transformer's 40VA rating before ordering. Questions about fitment? Our HVAC parts specialists verify compatibility before you order — contact us today and get your system back online fast.