OEM Carrier Transformer 40VA 120V–24V for Model FB4CNP036L00AAAA

This is the factory OEM replacement transformer (part number HT01CN241) for the Carrier FB4CNP036L00AAAA fan coil air handler. The transformer steps down 120V line voltage to the 24V signal voltage that powers your thermostat, control board, and all low-voltage switching circuits. When the transformer fails, the entire control circuit goes dark — the thermostat becomes unresponsive, the system won't heat or cool, and no error codes will display because the board itself has no power. A failed transformer is often misdiagnosed as a thermostat or control board issue, making it a critical first-check component.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Class 2 insulated | Matches factory-specified HT01CN241 exactly
• OEM vs Generic: OEM transformers are wound and insulated to Carrier's exact VA and thermal specifications. Generic units may be under-rated for VA load, leading to overheating, nuisance tripping, or premature failure — especially under multi-zone or communicating thermostat loads.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Note wire colors and terminal labels before disconnecting the old unit. Verify 24V output with a multimeter after installation before closing the panel.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier FB4CNP036L00AAAA fan coil air handler. Verify your existing transformer is rated 40VA 120V/24V by checking the data label on the transformer body before ordering. If your control board or thermostat still shows no power after replacement, also check for a shorted low-voltage wire causing repeated transformer failure. Our fitment team is available to confirm compatibility before you order — reach out before placing your order if you have any questions.