OEM Carrier 40VA Control Transformer for Model FIOP300511GA — Part HT01BD209

This OEM control circuit transformer is the factory-specified replacement for the Carrier FIOP300511GA unit. The transformer steps down line voltage (120V) to the 24V AC signal that powers your thermostat, control board, and all low-voltage switching components. When this part fails, the entire control circuit goes dark — the thermostat loses power, relays won't energize, and the system will not heat, cool, or respond to any commands. If nothing happens when you adjust the thermostat, a failed transformer is one of the first components to test.

• Specs: 120V primary | 24V secondary | 40VA rated | Factory OEM part number HT01BD209 | Direct plug-and-play replacement for Carrier FIOP300511GA
• OEM vs Generic: This is the exact factory transformer matched to Carrier's control circuit design. Generic transformers may carry incorrect VA ratings or use lower-grade windings, risking control board damage or nuisance tripping of the secondary fuse.
• Install Difficulty: 2/5 — Shut off all power at the disconnect and breaker before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 0V before touching terminals). Label or photograph all low-voltage wiring prior to disconnecting. Standard spade or screw terminal connections.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed and factory-matched for the Carrier FIOP300511GA. Verify your unit's data plate voltage requirements and existing transformer VA rating before ordering to ensure a correct fit. Our fitment team is available to confirm compatibility before you purchase — same-day shipping on all in-stock OEM parts.