OEM Carrier 40VA Control Transformer HT01CN241 for Model FX4DNF025T00AAAA

This OEM control transformer (part number HT01CN241) is the factory-specified replacement for the Carrier FX4DNF025T00AAAA fan coil air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers the entire low-voltage control circuit — including the thermostat, relay coils, and control board. When this component fails, the system will appear completely unresponsive: the thermostat goes dark, the air handler won't respond to any call for heating or cooling, and no low-voltage components will function. It is one of the first components to test when a system has total control failure with no obvious cause.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Class 2 transformer | Compatible with single-stage control circuits | Matches OEM dimensional and electrical profile exactly
• OEM vs Generic: This is a genuine OEM Carrier part built to factory specifications. Generic transformers often use lower-grade core laminations that run hot, reduce VA output under load, and fail prematurely — risking damage to downstream control boards and thermostats.
• Install difficulty: 2/5 — Power down the air handler at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or terminal connectors. Label or photograph all wiring connections before disconnecting the old unit. Verify 24V output at secondary terminals after installation before restoring the full system.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our stocked warehouse when ordered before cutoff.

Compatibility: Engineered as the direct OEM replacement for the Carrier FX4DNF025T00AAAA fan coil air handler. Always verify the transformer's VA rating and primary/secondary voltages against the data plate on your unit before ordering. Our fitment team is available to confirm compatibility before you buy — same-day shipping means your repair doesn't wait.