OEM Carrier Control Transformer 40VA 120V/24V for Model PY4GNAA48060AA

This is the factory OEM replacement transformer (part number HT01BD209) for the Carrier PY4GNAA48060AA packaged unit. The control transformer steps down line voltage from 120V to the 24V AC signal that powers your thermostat, control board, contactor coils, and all low-voltage control circuit components. When this transformer fails, the entire control circuit goes dark — the thermostat will not respond, the unit will not energize, and nothing will start. It is often the first component to diagnose when a system shows zero thermostat response with confirmed line voltage present at the unit.

• Specs: 120V primary | 24V secondary | 40VA rated | Direct OEM factory replacement for part number HT01BD209 | Class 2 control circuit transformer
• OEM vs Generic: This OEM unit is wound to Carrier's exact VA rating and insulation class, ensuring the control board and contactor coils receive clean, stable 24V. Generic transformers can run undervoltage under load, causing nuisance lockouts and premature contactor coil burnout.
• Install difficulty: 2/5 — Disconnect all power before servicing. Tools needed: multimeter (to confirm failed output voltage), flathead and Phillips screwdrivers, wire stripper. Label all low-voltage wires before removal. Confirm 24V output at secondary terminals after installation before restoring full power.
• Warranty: 1-year OEM factory warranty against defects. In-stock — ships same business day from our warehouse.

Compatibility: Designed for the Carrier PY4GNAA48060AA packaged unit. Always verify the OEM part number on your existing transformer's label before ordering. For fitment questions, our HVAC parts specialists are available to confirm compatibility before you buy.