OEM Carrier Control Transformer 40VA for Model FX4DNF043L10ACAA

This OEM step-down control transformer (part# HT01CN241) is the factory-specified replacement for the Carrier FX4DNF043L10ACAA air handler. The transformer converts 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and all low-voltage control circuits. When it fails, the entire control system goes dark — your thermostat goes blank, the air handler won't respond to any commands, and no heating or cooling stages will activate. A failed transformer is often misdiagnosed as a bad control board, so always test transformer output voltage first before replacing more expensive components.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Factory-matched OEM part number HT01CN241 | Class 2 transformer
• OEM vs Generic: OEM transformers from Carrier are wound to exact VA and voltage tolerances, ensuring stable 24V output under full control-circuit load. Generic units frequently deliver undervoltage at peak demand, causing intermittent lockouts and nuisance tripping of the transformer's internal fuse.
• Install difficulty: 2/5 — Disconnect power at the breaker and verify voltage is off before starting. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label or photograph all wiring connections before removal. The replacement mounts to the same bracket as the original and uses the same wire gauge.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before 3PM local time.

Compatibility: Engineered specifically for the Carrier FX4DNF043L10ACAA fan coil air handler. Verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate before ordering to ensure a correct fit. Have questions about compatibility? Our HVAC parts specialists confirm fitment before you buy — no guesswork.