OEM Carrier Control Transformer 40VA 120V/24V for Model FIOP100F311GA

This OEM replacement transformer (part number HT01BD209) is the factory-specified control circuit transformer for the Carrier FIOP100F311GA 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 components. When this part fails, the entire control circuit goes dead — the thermostat goes blank, contactors won't energize, and the system produces no response to any call for heating or cooling.

• Specs: 40VA rating | 120V primary / 24V secondary | Compatible with standard low-voltage control circuits | Factory-matched OEM construction for reliable, long-term operation
• OEM vs Generic: This is a genuine OEM Carrier transformer built to exact factory specifications. Generic transformers may carry incorrect VA ratings or use inferior core materials, leading to voltage sag under load and premature failure of connected control boards.
• Install difficulty: 2/5 — Disconnect all power before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Verify incoming voltage and confirm 24V output before reconnecting the control board. Always photograph existing wiring before removal.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier FIOP100F311GA unit. Confirm transformer VA rating and primary/secondary voltage on your unit's data plate or wiring diagram before ordering. If your thermostat screen is blank and your control board shows no activity, the transformer is the first component to test with a multimeter. Order with confidence — our HVAC parts team can verify fitment before you buy.