OEM Carrier 40VA Transformer HT01CN236 for Model FB4ANF030015AFAA

This OEM replacement transformer (part# HT01CN236) is the factory-specified control circuit transformer for the Carrier FB4ANF030015AFAA fan coil air handler. The transformer steps down line voltage from 120V to the 24V signal required to power the thermostat, control board, and all low-voltage relay logic. When it fails, the entire control circuit goes dead — the thermostat goes blank, contactors won't energize, and the system will not respond to any call for heating or cooling. A failed transformer is often misdiagnosed as a bad control board, making this an essential first diagnostic step.

• Specs: 40VA rating | 120V primary / 24V secondary | OEM part number HT01CN236 | Direct plug-in replacement — no field wiring modifications required
• OEM vs Generic: This OEM unit is wound to exact factory VA and voltage tolerances. Undersized or off-tolerance generic transformers can blow the low-voltage fuse repeatedly, cause erratic thermostat behavior, or fail prematurely under full control-circuit load.
• Install difficulty: 2/5 — Disconnect power at the disconnect box and verify voltage is absent with a multimeter before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Note wire colors and terminal positions before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier FB4ANF030015AFAA fan coil air handler. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. If you're unsure of fitment, our HVAC parts specialists are available to verify compatibility before you buy — same-day shipping on all in-stock orders.