OEM Carrier Control Transformer 120V/24V 40VA for Model PY3GNAA24040NA

This is the factory OEM replacement transformer (part number HT01BD209) for the Carrier PY3GNAA24040NA packaged unit. The control transformer steps down line voltage from 120V to the 24V AC signal that powers your thermostat, contactor coil, gas valve, and control board. When this transformer fails, the entire low-voltage control circuit goes dead — the system will not respond to thermostat calls, and nothing will operate. A failed transformer is often identified by a blown fuse on the control board, a burning smell near the air handler, or zero voltage measured on the 24V secondary terminals.

• Specs: 120V primary | 24V secondary output | 40VA rating | Factory OEM part number HT01BD209 | Direct plug-and-play replacement with OEM wiring harness compatibility
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact factory VA and voltage tolerances. Aftermarket transformers often run undersized VA ratings, causing overheating and premature failure under normal system loads.
• Install Difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning work. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Confirm 0V at terminals before touching any wiring. Photograph all connections prior to disconnecting the old transformer.
• Warranty: Backed by a 1-year OEM manufacturer warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for the Carrier PY3GNAA24040NA packaged unit. Always verify primary voltage and VA rating on your unit's data plate before ordering. Our HVAC parts specialists are available to confirm fitment — reach out before you order if you have any questions.