OEM Carrier Transformer 40VA 120V to 24V for Model FX4DNF031000AAAA

This OEM Carrier transformer (part number HT01CN241) is the factory-specified replacement for the FX4DNF031000AAAA fan coil air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, and all low-voltage switching components. When it fails, the entire control circuit goes dark — the thermostat displays nothing, the system won't respond to calls for heating or cooling, and in some cases a blown fuse or burning smell near the air handler is the first sign of trouble.

• Specs: 40VA rating | 120V primary input | 24V secondary output | Factory-matched winding and thermal protection | Replaces OEM part number HT01CN241
• OEM vs Generic: OEM transformers feature factory-wound coils and integrated thermal cutoffs matched to Carrier's control board draw. Generic units often lack adequate VA headroom, causing nuisance trips or premature burnout when multiple 24V accessories are wired in.
• Install difficulty: 2/5 — Disconnect power at the breaker and verify voltage is off before handling. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Label or photograph all low-voltage wire connections before removing the old transformer.
• Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our warehouse.

Compatibility: Engineered as a direct OEM replacement for the Carrier FX4DNF031000AAAA fan coil air handler. Verify your existing transformer is rated 40VA 120V/24V by checking the data label before ordering. If your control board fuse blew alongside the transformer, inspect for short circuits in the thermostat wiring before installing the new unit. Have a fitment question? Our HVAC parts team confirms compatibility before you order — call or chat today.