OEM Carrier Control Transformer 40VA 120V/24V for Model FK4CNF001000AGAA

This is the factory OEM replacement transformer (part number HT01CN236) for the Carrier FK4CNF001000AGAA fan coil air handler. The transformer steps down line voltage from 120V to the 24V AC signal required to power your thermostat, control board, and all low-voltage control circuits. When this component fails, the entire control circuit goes dark — your thermostat displays nothing, the system won't respond to any call for heating or cooling, and you may find a blown 3A or 5A low-voltage fuse upstream. Replacing this transformer restores full system communication and control.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Factory OEM part number HT01CN236 | Direct plug-in or wire-in mounting compatible with FK4CNF001000AGAA air handler cabinet
• OEM vs Generic: The OEM HT01CN236 transformer is wound to Carrier's exact VA rating and insulation class, ensuring no voltage sag under full control-circuit load. Generic transformers rated at nominal 40VA often underperform at peak demand, causing nuisance lockouts and thermostat brownouts.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter (to verify 24V output after install). Always check for a shorted low-voltage wiring harness before replacing — a downstream short will immediately blow the new transformer.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FK4CNF001000AGAA fan coil air handler. Verify your existing transformer's primary voltage (120V) and VA rating against your unit's data plate before ordering. If you have questions about fitment, our HVAC parts specialists verify compatibility before you place your order — no guesswork required.