OEM Carrier Transformer 40VA 120V to 24V for Model FH4BNF004000AAAA

This is the factory OEM replacement transformer (part number HT01CN241) for the Carrier FH4BNF004000AAAA air handler. The transformer steps down line voltage from 120V to 24V to power the low-voltage control circuit — including the thermostat, control board, and all 24V relays. When this component fails, the entire control system goes dark: your thermostat will show no response, the system won't call for heating or cooling, and no other troubleshooting steps will resolve the issue until power to the control circuit is restored. A failed transformer is often overlooked but is one of the fastest, most affordable fixes in HVAC service.

• Specs: 40VA rating | Primary voltage: 120V | Secondary voltage: 24V | OEM part number HT01CN241 | Factory-matched output for Carrier control circuits
• OEM vs Generic: This factory OEM transformer is wound to exact VA and voltage specifications. Generic transformers may have looser output tolerances, risking under-voltage faults that damage control boards and shorten thermostat life.
• Install difficulty: 2/5 — Shut off all power to the air handler at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm secondary 24V output after install). Photograph all wiring connections before disconnecting. Typical replacement time: 20–30 minutes.
• Warranty: 1-year OEM factory warranty against defects. In-stock units ship same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FH4BNF004000AAAA air handler. Always verify your existing transformer's VA rating, primary voltage, and secondary voltage from the data plate before ordering to ensure a correct fit. Our parts specialists are available to confirm compatibility before you purchase — same-day shipping available on all in-stock orders.