OEM Carrier 40VA Control Transformer HT01BD209 for Model PY4GPAA48115AA

The Carrier HT01BD209 is the factory OEM control transformer for the PY4GPAA48115AA packaged unit. It steps down line voltage from 208/230V on the primary side to a stable 24V AC output on the secondary side, powering the low-voltage control circuit that drives your thermostat, contactor coil, and all safety controls. When this transformer fails, the entire control circuit goes dark — symptoms include a completely unresponsive thermostat, no call-for-heat or call-for-cooling response, and a system that appears completely dead despite line voltage being present at the unit.

• Specs: 40VA rating | 208/230V primary | 24V secondary | 50/60 Hz | Direct OEM replacement — also replaces HT01BD207, HT01CN232, and 9076-00
• OEM vs Generic: The OEM HT01BD209 meets Carrier's exact VA rating and insulation class, ensuring the 24V rail stays stable under full control-circuit load. Undersized or off-spec generic transformers can brown out the control board under high-demand switching, causing intermittent lockouts.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label or photograph all wiring connections before removal. Confirm 24V output with a multimeter after install before closing the panel.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier PY4GPAA48115AA packaged unit. This transformer also cross-references to Carrier part numbers HT01BD207, HT01CN232, and 9076-00, making it a broad-fit OEM solution for Carrier, Bryant, and Payne equipment sharing this control circuit architecture. Always verify your unit's data plate voltage before ordering. Have questions about fitment? Our HVAC parts team verifies compatibility before you buy — contact us today and we'll ship your order out the same day.