OEM Carrier Transformer 40VA 120V/24V for Model FB4BNF048010AAAA

This is the factory OEM replacement transformer (part number HT01CN241) for the Carrier FB4BNF048010AAAA fan coil air handler. The transformer steps down line voltage from 120V to the 24V AC signal that powers your thermostat, control board, and all low-voltage system controls. When this component fails, the entire control circuit goes dead — your thermostat goes blank, the system will not respond to any commands, and nothing operates. If you have 120V at the primary but no 24V at the secondary, this transformer is almost certainly the cause.

• Specs: 40VA rated | 120V primary / 24V secondary | Factory-matched OEM part number HT01CN241 | Designed for Carrier fan coil air handler applications
• OEM vs Generic: This is a genuine Carrier OEM transformer built to exact VA and voltage tolerance specifications. Generic alternatives may be under-rated for VA load, causing premature failure or nuisance tripping of the secondary fuse — especially in multi-stage or zoned systems.
• Install difficulty: 2/5 — Shut off all power to the air handler before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter, wire nuts. Label or photograph all low-voltage wiring connections before disconnecting the old transformer. Confirm 120V supply before replacing.
• Warranty: 1-year OEM factory warranty against defects. In-stock orders ship the same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FB4BNF048010AAAA fan coil air handler. Verify your existing transformer's VA rating and primary/secondary voltage on the unit data plate or wiring diagram before ordering. Need help confirming fitment? Our HVAC parts specialists are ready to verify compatibility before you buy — same-day shipping available on all in-stock orders.