OEM Carrier 40VA Control Transformer for Model FX4DNF031T00ABAA

This OEM replacement transformer (Part# HT01CN241) is the factory-specified control transformer for the Carrier FX4DNF031T00ABAA air handler. It steps down 120V line voltage to 24V AC to power the control circuit, thermostat, and low-voltage components throughout your HVAC system. When this transformer fails, the entire control circuit loses power — the thermostat goes blank, the system won't respond to any calls for heating or cooling, and nothing works. A failed transformer is often the last thing technicians check, but it's one of the most common causes of a completely unresponsive system.

• Specs: 40VA rating | 120V primary / 24V secondary | Replaces OEM Part# HT01CN241 | Factory-matched output for stable, reliable low-voltage control power
• OEM vs Generic: This is the genuine factory OEM part. Generic transformers frequently underperform on VA rating, causing voltage sag under load that leads to intermittent lockouts, nuisance tripping of low-voltage fuses, and premature failure of downstream control boards.
• Install Difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 24V output after install). Label all wiring before disconnecting. Check and replace any blown inline 3A or 5A low-voltage fuse before restoring power.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Engineered as the direct factory replacement for the Carrier FX4DNF031T00ABAA residential air handler. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate before ordering. If you're unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you buy — same-day shipping on all in-stock orders.