OEM Carrier Transformer 40VA 120V–24V Control Circuit for Model FA4ANF018000AFAA

This is the factory OEM replacement transformer (part# HT01CN236) for the Carrier FA4ANF018000AFAA air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, and all low-voltage control circuits. When this component fails, the entire control circuit goes dark — your thermostat becomes unresponsive, the system won't call for heating or cooling, and nothing happens when you adjust the setpoint. A failed transformer is often misdiagnosed as a faulty control board, making this an important first diagnostic step.

• Specs: 40VA rating | 120V primary / 24V secondary | Factory-matched OEM design | Part number HT01CN236 — direct drop-in replacement for Carrier FA4ANF018000AFAA air handlers
• OEM vs Generic: OEM transformers are wound and potted to exact factory specifications, ensuring stable 24V output under full load. Generic units frequently deliver fluctuating voltage that can damage sensitive control boards and shorten thermostat life.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Use your multimeter to confirm 0V at the primary leads before touching any wiring. Note existing wire connections before removal.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our climate-controlled warehouse.

Compatibility: Designed specifically for the Carrier FA4ANF018000AFAA fan coil air handler. Confirm your unit's data plate shows a 120V/24V, 40VA transformer requirement before ordering. If you're unsure of fitment, our HVAC parts team is available to verify compatibility before you buy — no guesswork required.