OEM Carrier Transformer 40VA 120V to 24V for Model FX4DNF025000AAAA

This is the factory OEM replacement transformer (part number HT01CN241) for the Carrier FX4DNF025000AAAA air handler. The transformer steps down line voltage (120V) to the 24V AC signal that powers your entire control circuit — including the thermostat, contactor coil, gas valve, and control board. When this transformer fails, absolutely nothing responds: the thermostat goes blank, no heating or cooling stages activate, and the system is completely dead. It is one of the most commonly overlooked failure points in an HVAC diagnostic.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN241 | Factory-matched for Carrier air handlers
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the factory control board. Undersized or off-tolerance generic units can cause erratic cycling, nuisance lockouts, or premature control board failure — making the OEM choice the safer long-term investment.
• Install Difficulty: 2/5 — Shut off all power to the air handler before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 24V output after installation). Label or photograph all low-voltage wiring connections before removing the old transformer.
• Warranty: 1-year OEM factory warranty included. Orders placed before cutoff ship same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FX4DNF025000AAAA fan coil air handler. Always verify the VA rating and voltage specs on your unit's data plate before ordering. If you're unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you buy — no guesswork required. In stock and ready to ship today.