OEM Carrier Transformer 40VA 120V–24V for Model HC1BNX042000AAAA

This OEM replacement transformer (part number HT01AW229) is the factory-specified control circuit transformer for the Carrier HC1BNX042000AAAA fan coil unit. The transformer steps line voltage (120V) down to the 24V signal voltage required by the thermostat, control board, and all low-voltage components throughout the system. When this transformer fails, the entire control circuit loses power — the thermostat goes blank, the system refuses to respond to any calls for heating or cooling, and no contactors or relays will energize. It is often the first component to inspect when a system appears completely dead despite normal line voltage at the unit.

• Specs: 40VA rated | 120V primary input | 24V secondary output | Factory-matched impedance and insulation class for Carrier HC1BNX042000AAAA
• OEM vs Generic: OEM transformers (HT01AW229) are wound to exact factory VA and thermal specifications. Generic substitutes often underrate VA capacity, causing premature thermal shutoff under full control-circuit load — particularly in multi-stage or communicating systems.
• Install difficulty: 2/5 — Disconnect all power before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Confirm 0V at transformer terminals before handling. Photograph all wiring connections prior to removal.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our HVAC parts warehouse.

Compatibility: Designed specifically for the Carrier HC1BNX042000AAAA fan coil unit. Verify your existing transformer's VA rating and primary/secondary voltages on the data plate before ordering. If you're unsure of fitment, our technical team is available to confirm compatibility before you purchase — same-day shipping available on all in-stock OEM parts.