OEM Carrier Control Transformer 120V–24V 40VA for Model PY3PPA030040AB

This is the OEM factory-replacement control transformer (part number HT01BD209) for the Carrier PY3PPA030040AB packaged unit. The transformer steps down 120V line voltage to the 24V signal voltage required to power the thermostat, control board, and all low-voltage switching circuits. When this component fails, the entire control circuit goes dark — the thermostat becomes unresponsive, contactors won't energize, and the system will not heat or cool regardless of thermostat input. A failed transformer is one of the first components to check when a system shows zero response to any thermostat command.

• Specs: Input 120V AC | Output 24V AC | 40VA rated | OEM part number HT01BD209 | Factory-matched windings and insulation class for Carrier specifications
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact factory VA and voltage tolerances. Generic aftermarket transformers often run under-rated VA, which can cause nuisance tripping of the internal thermal overload or premature failure under peak control-circuit demand.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Label all low-voltage wiring before disconnecting. Verify output voltage with a multimeter after installation before restoring control-circuit connections.
• Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our warehouse.

Compatibility: Designed and factory-specified for the Carrier PY3PPA030040AB packaged unit. Always verify your unit's data plate voltage and VA requirements before ordering. Our parts specialists are available to confirm fitment — contact us before you order if you have any questions.