OEM Carrier Transformer 40VA 120V to 24V for Model FX4DNF043L00ACAA

This is the factory OEM replacement transformer (part number HT01CN241) for the Carrier FX4DNF043L00ACAA fan coil air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers your entire control circuit — including the thermostat, contactor coil, and all low-voltage safety controls. When this transformer fails, nothing in the system responds: the thermostat goes dark, the air handler won't call for cooling or heating, and no components energize. A failed transformer is often misdiagnosed as a bad thermostat or control board, making it one of the first components to test during a no-power diagnostic.

• Specs: 40VA rated | 120V primary / 24V secondary | OEM part number HT01CN241 | Factory-matched output for Carrier low-voltage control circuits
• OEM vs Generic: This OEM transformer is wound and rated to exact Carrier factory specifications. Generic transformers frequently underperform under sustained load, causing nuisance low-voltage faults, control board resets, or premature secondary winding failure — especially in multi-stage or communicating systems.
• Install difficulty: 2/5 — Shut off all power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter to confirm 24V output after install. Label all low-voltage wires before disconnecting. Typical replacement time: 20–30 minutes.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FX4DNF043L00ACAA fan coil air handler. Always verify your existing transformer's VA rating and voltage on the unit data plate or old component label before ordering. If you have questions about fitment, our parts specialists confirm compatibility before you buy — no guesswork.