OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY4GNAA30040AA

This factory-original OEM control transformer (part #HT01BD209) is the direct-fit replacement for the Carrier PY4GNAA30040AA packaged unit. The transformer steps down high-voltage line power (208/240V) to the 24V AC signal that energizes your system's entire control circuit — thermostat, contactor coils, gas valve, and control board alike. When this transformer fails, the result is typically a completely unresponsive system: the thermostat goes blank, no heating or cooling calls are answered, and the unit sits dead even with line voltage present at the disconnect.

• Specs: Input 208/240V | Output 24V secondary | 40VA power rating | 50/60Hz | OEM part number HT01BD209 | Factory-matched Carrier specification
• OEM vs Generic: OEM transformers are wound and insulated to exact Carrier factory tolerances. Generic or aftermarket units frequently run outside ±5% voltage output tolerance, which can cause nuisance tripping of downstream boards and shorten contactor coil life.
• Install difficulty: 2/5 — Always shut off line-voltage power at the disconnect and verify zero volts with a multimeter before touching any wiring. Photograph all wiring connections before disconnecting the old transformer. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Re-verify 24V output after install before closing the cabinet.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier PY4GNAA30040AA packaged units. Always confirm your unit's data plate voltage matches the 208/240V primary specification before ordering. Need fitment help? Our HVAC parts specialists verify compatibility before you buy — contact us today.