OEM Carrier Transformer 40VA 120V to 24V for Model FX4DNB043T00AAAA

This is the factory OEM replacement transformer (part number HT01CN241) for the Carrier FX4DNB043T00AAAA air handler. The transformer steps down line voltage (120V) to low-voltage 24VAC, powering the entire control circuit — including the thermostat, contactor coil, and control board relay logic. When the transformer fails, the system goes completely unresponsive: the thermostat goes dark, no call for heating or cooling is processed, and the unit will not operate in any mode. A failed transformer is often the first suspect when nothing works and the circuit breaker is confirmed on.

• Specs: 40VA rated | 120V primary / 24V secondary | Factory OEM matched to Carrier FX4DNB043T00AAAA | Part No. HT01CN241 | Hardwired leads for direct drop-in replacement
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances specified by Carrier engineering. Undersized or off-tolerance generic units can overheat, trip internal fuses, or cause erratic control board behavior — problems that can be misdiagnosed as a failed board.
• 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). Label or photograph all wiring connections before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FX4DNB043T00AAAA air handler. Always verify your unit's data plate voltage and VA rating before ordering. If you are unsure of fitment, our parts specialists can confirm compatibility before you purchase — just reach out before placing your order.