OEM Carrier Control Transformer 40VA 208/230V–24V for Model PY3PPA048115NB

This is the genuine OEM Carrier control transformer (part #HT01BD209) factory-specified for the Carrier PY3PPA048115NB packaged unit. The transformer steps down 208/230V line voltage to the 24V low-voltage signal that powers your thermostat, control board, contactor coil, and every other safety circuit in the system. When this transformer fails — whether from a shorted control wire, a failed component drawing excess current, or simple age — the entire low-voltage circuit goes dead. Symptoms include a completely unresponsive thermostat, a system that won't energize in any mode, or a blown low-voltage fuse that keeps returning.

• Specs: 40VA capacity | 208/230V primary input | 24V secondary output | 50/60 Hz | OEM part #HT01BD209 | Also cross-references HT01BD207, HT01CN232, 4000A46E07AE28, and 9076-00
• OEM vs Generic: OEM transformers are wound to Carrier's exact VA and impedance ratings. Undersized or off-tolerance generic units can overheat, trip thermal protection, or fail to hold 24V under load — causing intermittent lockouts that are extremely difficult to diagnose.
• Install difficulty: 2/5 — Always shut off 120V power at the disconnect before working in the control compartment. Tools needed: flathead and Phillips screwdriver, multimeter, wire labels. Before disconnecting, photograph all wiring. Inspect all low-voltage wiring for shorts that may have caused the original failure — replacing the transformer without fixing the root cause will blow the new one too.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before cutoff.

Compatibility: Designed as the factory replacement for Carrier model PY3PPA048115NB packaged gas/electric units. Verify your unit's data plate shows 208/230V single-phase power and 24V control circuit before ordering. Questions about fitment? Our team confirms compatibility before you buy — no guessing required.