OEM Carrier Transformer 40VA 24V for Air Handler Model FV4BNB005000AAAA

This OEM replacement transformer (part number HT01CN236) is the factory-specified control circuit transformer for the Carrier FV4BNB005000AAAA fan coil air handler. The transformer steps down line voltage (120V) to the 24V AC signal that powers your thermostat, control board, and all low-voltage switching components. When this transformer fails, the entire control circuit goes dark — your thermostat will appear dead, your system will not respond to any call for heating or cooling, and no fault codes will display on the board because there is simply no power to generate them.

• Specs: 40VA rated | 120V primary input | 24V secondary output | OEM part number HT01CN236 | Factory-matched voltage and VA rating for full control circuit compatibility
• OEM vs Generic: OEM transformers are wound and insulated to Carrier's exact VA tolerance, protecting downstream components like the control board and contactor coil from undervoltage stress. Generic units may be rated loosely, causing nuisance lockouts or premature board failure.
• Install difficulty: 2/5 — Shut off all power to the air handler before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 0V before touching terminals). Photograph or label all low-voltage wire connections prior to removal. Swap wires one at a time to avoid miswiring.
• Warranty: 1-year OEM factory warranty. In-stock units ship the same business day from our warehouse.

Compatibility: Designed and tested for the Carrier FV4BNB005000AAAA fan coil air handler. Always verify your existing transformer's VA rating and voltage markings on the unit data plate before ordering to confirm a direct fit. Have questions about fitment? Our HVAC parts specialists verify compatibility before you buy — reach out before placing your order.