OEM Carrier Control Transformer 40VA 208/240V to 24V — HT01BD209 for Model PY4GNAA60090AA

This genuine OEM Carrier control transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PY4GNAA60090AA packaged unit. The transformer steps down line voltage (208/240V primary) to a safe 24V secondary signal that powers your thermostat, control board, and all low-voltage control circuitry. When this transformer fails, the entire control circuit loses power — resulting in a completely unresponsive system: the thermostat goes blank, no heating or cooling stages activate, and no error codes are displayed because the board itself has no power to communicate.

• Specs: 208/240V Primary | 24V Secondary | 40VA rating | 50/60 Hz | OEM part # HT01BD209 | Replaces HT01BD207, HT01CN232, and 9076-00
• OEM vs Generic: OEM transformers are wound to exact VA and impedance tolerances required by Carrier's control board. Undersized or off-tolerance generic transformers can cause nuisance tripping, control board brownouts, or accelerated board failure — always use OEM when the control board is involved.
• Install difficulty: 2/5 — Shut off power at the disconnect before beginning. Tools needed: multimeter (to verify 0V before touching wiring), flathead and Phillips screwdrivers, needle-nose pliers, wire nuts or spade terminals. Photograph all wiring before disconnecting. Verify 24V output at secondary terminals before reassembling the unit.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Factory-matched for Carrier model PY4GNAA60090AA packaged unit. Always verify your unit's data plate voltage matches 208/240V primary input before ordering. Cross-references: HT01BD207, HT01CN232, 9076-00, 4000A46E07AE28. Questions about fitment? Our HVAC parts team confirms compatibility before you order — reach out before purchasing.