OEM Carrier Transformer 40VA 120V to 24V for Model FIOP100B311GA

This is the factory OEM replacement transformer (part number HT01BD209) for the Carrier FIOP100B311GA. The transformer steps down line voltage (120V) to the 24V low-voltage signal required to power the control board, thermostat, and all control circuit components. When this part fails, the entire control circuit goes dark — your thermostat will appear dead, the system will not respond to any call for heating or cooling, and no error codes will display because the board itself has no power.

• Specs: Input: 120VAC | Output: 24VAC | VA Rating: 40VA | OEM Part Number: HT01BD209 | Factory-matched primary and secondary winding specifications
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the Carrier FIOP100B311GA control circuit. Undersized or off-spec generic transformers can overload and fail prematurely, or provide insufficient voltage to reliably operate the gas valve and contactor coils.
• Install difficulty: 2/5 — Always disconnect power at the breaker before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 0V before touching wiring). Photograph all wiring connections before disconnecting. The transformer mounts to the cabinet panel and connects inline with the control board harness.
• Warranty: 1-year OEM factory warranty against defects. Orders placed before cutoff ship same business day from our stocked warehouse.

Compatibility: This OEM transformer is specifically matched to the Carrier FIOP100B311GA. Verify your unit's data plate confirms 120V primary input and 24V secondary output before ordering. If your system uses a 208/240V primary input transformer, this unit will not be compatible — confirm input voltage before purchase. Our fitment team is available to verify compatibility before you order.