OEM Carrier 40VA Control Transformer HT01CN241 for Model FX4DNF049010AAAA

This OEM Carrier control transformer (part number HT01CN241) is the factory-specified replacement for the FX4DNF049010AAAA fan coil air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and every other low-voltage component in the system. When it fails, the entire control circuit goes dark — the thermostat loses communication, the system won't respond to any call for heating or cooling, and no diagnostic codes are generated because the board itself has no power.

• Specs: 40VA rating | 120V primary / 24V secondary | Factory-matched output tolerance | Replaces OEM part number HT01CN241
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the Carrier control board. Undersized or off-tolerance generic units can trip thermal protection under load, cause intermittent lockouts, or damage sensitive board components over time.
• Install Difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter to verify 24V output after install. Photograph all wiring connections before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our climate-controlled warehouse.

Compatibility: Designed and factory-matched for the Carrier FX4DNF049010AAAA fan coil air handler. Verify your existing transformer's primary/secondary voltage and VA rating against your unit's data plate before ordering. If your system has no 24V signal and all fuses check good, this transformer is the most common cause. Our fitment team is available to confirm compatibility before you purchase — same-day shipping on all in-stock orders.