OEM Carrier 40VA Control Transformer HT01CN241 for Model FX4DNF043T00AAAA

This is the factory OEM replacement control transformer (part number HT01CN241) for the Carrier FX4DNF043T00AAAA fan coil air handler. The transformer steps down 120V line voltage to 24V AC to power the low-voltage control circuit — including the thermostat, contactor coil, and control board. When this transformer fails, the entire control system goes dark: the thermostat loses power, the system won't respond to calls for cooling or heating, and nothing operates. If you're measuring 120V at the air handler but getting no 24V signal at the thermostat terminals, a failed transformer is the most common cause.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN241 | Factory-matched output tolerance for reliable low-voltage control
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact factory VA and voltage specifications. Generic transformers often run under-rated VA, causing overheating and premature failure when multiple control accessories draw from the circuit simultaneously.
• Install Difficulty: 2/5 — Shut off power at the breaker and verify with a non-contact voltage tester before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Photograph all wiring connections before disconnecting the old transformer. Mount in the same orientation as the original.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. In-stock and ships same business day from our climate-controlled warehouse.

Compatibility: Engineered specifically for the Carrier FX4DNF043T00AAAA fan coil air handler. Always verify your existing transformer's primary/secondary voltage and VA rating against your unit's data plate before ordering. Our HVAC parts specialists are available to confirm fitment — contact us before you order if you have any questions. Order today and receive free same-day shipping on all in-stock parts.