OEM Carrier 40VA Control Transformer HT01BD209 for Model PY3PPA048090AB

This OEM control transformer is the factory-specified replacement for the Carrier PY3PPA048090AB 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 safety circuits. When it fails, the entire control circuit goes dark — the thermostat goes blank, the system won't respond to any calls for heating or cooling, and nothing works. It is one of the first components to inspect when troubleshooting a completely unresponsive unit.

• Specs: 40VA rating | 120V primary / 24V secondary | Factory-matched OEM part number HT01BD209 | Quick-connect or screw terminal leads depending on production date
• OEM vs Generic: This is a genuine OEM Carrier transformer built to exact VA, voltage, and thermal-overload specifications. Generic substitutes often carry lower VA ratings or inferior thermal protection, risking repeated failure or downstream control board damage.
• Install difficulty: 2/5 — Always disconnect power at the breaker before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after install). Photograph or label all wiring before removal. Discharge any residual voltage and confirm primary/secondary terminals match before energizing.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed for Carrier model PY3PPA048090AB packaged gas/electric units. Always verify the part number on your existing transformer's label and cross-reference with your unit's data plate before ordering. Our HVAC parts specialists are available to confirm fitment prior to purchase — we want to make sure you get the right part the first time.