OEM Carrier Transformer 40VA for Model FX4DNF049L00ABAA — Part HT01CN241

This OEM step-down transformer (part HT01CN241) is the factory-specified replacement for the Carrier FX4DNF049L00ABAA air handler. The transformer converts 120V line voltage to the 24V AC signal that powers the entire control circuit — including the thermostat, control board, zone valves, and relay coils. When this part fails, absolutely nothing in the system responds: the thermostat goes blank, the air handler won't energize, and no call for heating or cooling will be acknowledged. If you've verified your breaker is on and your thermostat batteries are good but the system is completely dead, a failed transformer is the most likely culprit.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Replaces OEM part number HT01CN241 | Factory-matched output tolerance for reliable control circuit operation
• OEM vs Generic: This is the genuine Carrier OEM transformer, built to exact factory VA and voltage specifications. Generic transformers may be undersized in VA rating, causing overheating and premature failure — especially in multi-zone or communicating systems with higher control circuit loads.
• Install difficulty: 2/5 — Turn off power at the breaker and confirm voltage is absent with a multimeter before starting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire nuts or quick-connects, multimeter. Photograph all wiring connections before disconnecting. Secondary output should read 24–28V AC when energized.
• Warranty: 1-year OEM factory warranty. Ships same business day from our NationalHVACParts.com warehouse when ordered before the daily cutoff.

Compatibility: Engineered for the Carrier FX4DNF049L00ABAA multi-position air handler. Always verify your existing transformer's VA rating and primary voltage from the unit's data plate or wiring diagram before ordering. Our parts specialists are available to confirm fitment — reach out before you buy if you have any questions.