OEM Carrier Transformer 40VA 120V–24V for Model C4850C50Z7090610

This is the factory-original replacement transformer (OEM part# HT01BD236) for the Carrier C4850C50Z7090610 packaged unit. The transformer steps down line voltage (120V) to the 24V control circuit voltage that powers your thermostat, contactor coil, and all low-voltage switching. When this component fails, the entire control circuit goes dark — you'll see a blank thermostat display, no response to any call for heating or cooling, and potentially a tripped secondary fuse. It is often the first part to diagnose when absolutely nothing in the system responds.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | OEM part number HT01BD236 | Direct drop-in replacement, no wiring modification required
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact VA and voltage specifications. Generic transformers are frequently under-rated in VA output, causing premature overheating and failure when paired with modern multi-stage controls and zone boards that draw higher sustained current.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flat-head and Phillips screwdrivers, multimeter (to verify 24V output after install), wire nuts or spade connectors. Photograph existing wiring before disconnecting. Secondary circuit fuse should also be inspected and replaced if blown.
• Warranty: 1-year OEM manufacturer warranty. In stock and ships same business day from our warehouse.

Compatibility: Engineered specifically for the Carrier C4850C50Z7090610 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate before ordering. If you are unsure of fitment, our parts team will confirm compatibility before your order ships — no guesswork required.