OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY3GNAA48090NA

This is the genuine OEM Carrier control transformer (part #HT01BD209) factory-specified for the Carrier PY3GNAA48090NA packaged gas/electric unit. The transformer steps down line voltage (208/240V) to the 24V AC signal that powers your thermostat, control board, gas valve, and all low-voltage control circuit components. When this transformer fails, the entire control circuit goes dark — you'll see a blank thermostat display, no system response to calls for heating or cooling, and potentially a blown 3A or 5A fuse on the control board indicating a downstream short.

• Specs: 208/240V primary input | 24V secondary output | 40VA rating | 50/60 Hz | OEM part #HT01BD209 | Replaces HT01BD207, HT01CN232, and 4000A46E07AE28
• OEM vs Generic: OEM transformers are wound to exact VA tolerance, protecting your control board from voltage sag under load. Generic units often run undersized, causing nuisance lockouts, erratic thermostat behavior, and premature board failure — especially on multi-stage systems.
• Install difficulty: 2/5 — Shut off power at the disconnect and verify zero voltage with a multimeter before touching any terminals. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Always photograph wiring before disconnecting. Inspect fuses before replacing the transformer — a blown fuse usually signals a wiring short that must be corrected first.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before 3PM local time.

Compatibility: Designed for the Carrier PY3GNAA48090NA packaged unit. Also compatible with select Bryant and Payne models using the same 208/240V-to-24V, 40VA transformer specification — verify your unit's data plate voltage and VA requirements before ordering. Our fitment team is available to confirm compatibility before you buy.