OEM Carrier Transformer 40VA 120V to 24V for Model FV4BNF003000AAAA

This OEM replacement transformer (part# HT01CN236) is the factory-specified step-down transformer for the Carrier FV4BNF003000AAAA fan coil air handler. Its job is critical: it converts 120V line voltage down to the 24V AC signal that powers your thermostat, control board, and all low-voltage control circuits. When the transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system won't respond to any commands, and nothing turns on. If you've confirmed 120V at the unit but zero 24V output, this part is almost certainly the culprit.

• Specs: Primary voltage 120V AC | Secondary voltage 24V AC | 40VA rated | OEM part number HT01CN236 | Factory-matched output tolerance for reliable low-voltage control
• OEM vs Generic: OEM transformers are wound and rated to exact factory specifications, ensuring stable 24V output under full load. Off-brand substitutes often run undervoltage, causing intermittent lockouts, nuisance tripping of the control board, and premature contactor failure.
• Install difficulty: 2/5 — Shut off all power to the air handler before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label or photograph all wiring connections before disconnecting. Verify 24V output with a multimeter after installation before closing the cabinet.
• Warranty: 1-year OEM factory warranty against defects. Orders placed before cutoff ship same business day from our climate-controlled parts warehouse.

Compatibility: Engineered as the direct OEM replacement for Carrier FV4BNF003000AAAA fan coil air handlers. Always verify primary voltage, secondary voltage, and VA rating on your unit's data plate before ordering. Our parts specialists are available to confirm fitment — reach out before you buy if you have any questions.