OEM Carrier Transformer 40VA 120V-24V for Model FX4DNF037L10ABAA

This OEM replacement transformer (part number HT01CN241) is the factory-specified control circuit transformer for the Carrier FX4DNF037L10ABAA air handler. The transformer steps down line voltage from 120V to 24V AC to power the entire low-voltage control circuit — including the thermostat, control board, and contactor coil. When this component fails, the entire system goes dark: the thermostat loses power, no calls for heating or cooling are processed, and the unit will not operate at all. A faulty transformer is often diagnosed by checking for 24V output at the secondary terminals with a multimeter; zero output with 120V input confirms transformer failure.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN241 | Factory-matched output tolerance for stable low-voltage control
• OEM vs Generic: This OEM unit is wound to Carrier's exact VA rating and insulation class, ensuring full ampacity for all low-voltage loads. Generic transformers are frequently undersized in VA capacity, causing overheating, nuisance breaker trips on the secondary circuit, and premature failure.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter, wire nuts. Label all 24V wiring connections before removing the old unit. Confirm 120V input and 24V output after installation before closing the cabinet.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our NationalHVACParts.com warehouse.

Compatibility: Engineered as a direct OEM replacement for the Carrier FX4DNF037L10ABAA fan coil air handler. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or existing part label before ordering. Our fitment team is available to confirm compatibility before you buy — order with confidence and get back up and running today.