OEM Carrier Transformer 40VA 120V to 24V for Model FX4CNF042T00AAAA

This OEM replacement transformer (part number HT01CN241) is the factory-specified step-down transformer for the Carrier FX4CNF042T00AAAA fan coil air handler. The transformer converts 120V line voltage to the 24V AC signal that powers the entire low-voltage control circuit — including the thermostat, contactor coil, and control board. When this transformer fails, the system goes completely silent: the thermostat loses power, no calls for heating or cooling are processed, and nothing operates. A failed transformer is often mistaken for a thermostat or control board issue, making it the first component to diagnose when the system has zero response.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Class 2 transformer | OEM part number HT01CN241 | Factory-matched output tolerance
• OEM vs Generic: OEM transformers from Carrier are wound and insulated to exact VA and voltage specifications. Generic replacements can run low on VA output under load, causing voltage sag that triggers nuisance lockouts or premature control board failure.
• Install difficulty: 2/5 — Always disconnect power at the breaker before servicing. Tools needed: flathead and Phillips screwdriver, multimeter (to verify 24V output after install), wire nuts or spade connectors. Photograph existing wiring before disconnecting. Note polarity markings on primary and secondary leads.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Engineered specifically for the Carrier FX4CNF042T00AAAA fan coil air handler. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. Our fitment team is available to confirm compatibility before you buy — same-day shipping on all in-stock orders.