OEM Carrier 40VA Control Transformer HT01CN236 for Model FK4CNF002000AGAA

This is the factory OEM replacement transformer (part# HT01CN236) for the Carrier FK4CNF002000AGAA air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and every other low-voltage component in the system. When this transformer fails, absolutely nothing responds — the thermostat goes blank, the system won't call for heating or cooling, and no fault codes appear because the control board itself has lost power. If you've already ruled out a tripped breaker and a blown fuse, this transformer is the next component to test with a multimeter.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN236 | Factory-matched to Carrier FK4CNF002000AGAA air handler
• OEM vs Generic: OEM transformers are wound and potted to Carrier's exact VA rating and thermal protection specs. Undersized or off-tolerance generic transformers can overheat, blow the low-voltage fuse repeatedly, or damage sensitive control boards over time.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire nuts or spade connectors, and a multimeter to confirm output voltage after installation. Label all wires before removing the old unit.
• Warranty: 1-year OEM factory warranty against defects. In-stock units ship same business day when ordered before 3 PM local time.

Compatibility: Designed specifically for the Carrier FK4CNF002000AGAA fan coil/air handler. Always verify your existing transformer's VA rating and primary/secondary voltages on the data plate or wiring diagram before ordering. Our fitment team is available to confirm compatibility before you purchase — no guesswork required.