OEM Carrier Transformer 40VA 120V to 24V for Model FA4ANF030010AGAA

This is the factory OEM replacement transformer (part number HT01CN236) for the Carrier FA4ANF030010AGAA air handler. The transformer steps down 120V line voltage to the 24V signal voltage that powers your entire control circuit — including the thermostat, contactor coils, and control board. When this transformer fails, the result is total system silence: the thermostat goes dark, nothing responds, and no heating or cooling cycle can begin. A failed transformer is often misdiagnosed as a thermostat or control board fault, making it one of the most overlooked components in HVAC service.

• Specs: 40VA rated | 120V primary / 24V secondary | OEM part number HT01CN236 | Factory-matched output voltage tolerance for stable control circuit operation
• OEM vs Generic: This OEM unit is wound to Carrier's exact VA and voltage specifications. Generic transformers often run at lower actual VA output, causing nuisance tripped fuses and intermittent control failures under full load — especially when multiple zone valves or relay coils are energized simultaneously.
• Install difficulty: 2/5 — Shut off power at the breaker and confirm with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Photograph all wiring before disconnecting. Check and replace the 3A or 5A control fuse while the transformer is out.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier FA4ANF030010AGAA air handler. Always verify your unit's data plate voltage requirements and VA rating match before ordering. If your system includes zone controls or multiple accessories, confirm total connected VA load does not exceed 40VA. Need fitment help? Our parts team confirms compatibility before you buy.