OEM Carrier Transformer 40VA 120V–24V for Model FX4DNB043L00ABAA

This OEM replacement transformer (part# HT01CN241) is the factory-specified control circuit transformer for the Carrier FX4DNB043L00ABAA fan coil air handler. It steps down 120V line voltage to the 24V signal required by the control board, thermostat, and all low-voltage control circuits. When this transformer fails, the entire system goes dark — the thermostat loses power, the air handler won't respond to any call for heating or cooling, and no error codes can even be generated. It is one of the first components to check when absolutely nothing in the system responds.

• Specs: 40VA rated | 120V primary / 24V secondary | Single-phase | Factory-matched OEM tolerances | OEM Part Number: HT01CN241
• OEM vs Generic: This OEM unit is wound and insulated to Carrier's exact VA and voltage specifications. Undersized or off-tolerance generic transformers can overheat, blow internal fuses, and damage downstream control boards — a far costlier repair than the transformer itself.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdriver, needle-nose pliers, multimeter. Verify 24V output across secondary terminals after installation before restoring full power.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM drop-in replacement for the Carrier FX4DNB043L00ABAA fan coil air handler. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. Our parts specialists are available to confirm fitment prior to purchase — reach out before you order if you have any questions.