OEM Carrier Control Transformer 40VA for Model FB4CNF018L05ABAA

This OEM control transformer (part number HT01CN241) is the factory-specified replacement for the Carrier FB4CNF018L05ABAA air handler. The transformer steps down line voltage (120V) to the 24V AC signal that powers your thermostat, control board, and every relay in the system. When this component fails, the result is total system silence — your thermostat goes blank, nothing responds to calls for heating or cooling, and the control board loses all power. It is one of the first components to check when the entire system appears completely dead.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN241 | Direct plug-in or screw-mount replacement — matches factory wiring harness and bracket footprint exactly
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to factory VA and voltage specifications. Generic transformers often run undersized VA ratings, causing overheating, nuisance tripping of the built-in thermal fuse, and premature failure — especially in systems with multiple 24V accessories such as zone boards or humidifiers.
• Install Difficulty: 2/5 — Shut off power at the breaker and confirm voltage is absent before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or terminal connectors. Label all low-voltage wiring before disconnecting. Confirm secondary output reads 24–28V AC after installation before restoring thermostat.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. In stock and ships same business day from our warehouse.

Compatibility: Engineered specifically for the Carrier FB4CNF018L05ABAA residential air handler. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate or wiring diagram before ordering. Need help confirming fitment? Our HVAC parts team is available to verify compatibility before you buy — same-day shipping available on all in-stock orders.