OEM Carrier Transformer 40VA 120V–24V for Model FB4BNF036010AAAA

This OEM replacement transformer (part number HT01CN241) is the factory-specified step-down transformer for the Carrier FB4BNF036010AAAA fan coil air handler. The transformer converts 120V line voltage down to the 24V AC signal that powers your control board, thermostat, and all low-voltage control circuits. When the transformer fails, the entire control circuit loses power — the thermostat goes dark, the system won't respond to any calls for heating or cooling, and no safety safeties or relays will energize. A failed transformer is often misdiagnosed as a bad control board, so always verify 24V output at the secondary terminals before replacing more expensive components.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN241 | Factory-matched output tolerance for reliable low-voltage circuit performance
• OEM vs Generic: This OEM unit is wound and rated to exact Carrier specifications. Generic transformers often carry inferior core materials and loose VA ratings, which can cause voltage sag under load, leading to nuisance lockouts and premature control board failure.
• Install Difficulty: 2/5 — Shut off power at the breaker and disconnect switch before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or terminal connectors. Label all wiring before removal. Verify 24V output with a multimeter after installation before restoring full system power.
• Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our warehouse.

Compatibility: Engineered for the Carrier FB4BNF036010AAAA fan coil air handler. Verify your existing transformer's VA rating and primary/secondary voltages against your unit's data plate before ordering. Our fitment team is available to confirm compatibility before you buy — same-day shipping available on all in-stock orders placed before 3 PM local time.