OEM Carrier 40VA Control Transformer for Model C4850C50AJ03061

This OEM replacement transformer (part# HT01BD236) is the factory-specified step-down transformer for the Carrier C4850C50AJ03061 packaged unit. The transformer converts 120V line voltage to the 24V AC signal that powers your entire control circuit — including the thermostat, contactor coil, gas valve, and all safety switches. When the transformer fails, the entire system goes silent: the thermostat goes blank, no calls for heat or cool are responded to, and the unit will not energize under any mode. A blown transformer is often the single point of failure behind a completely unresponsive HVAC system.

• Specs: 40VA rating | 120V primary / 24V secondary | Class 2 output | OEM part number HT01BD236 | Factory-matched construction for Carrier packaged units
• OEM vs Generic: This is a genuine OEM Carrier transformer engineered to exact VA rating and insulation class. Generic transformers may be undersized in VA capacity, causing overheating under full control-circuit load and premature failure — especially in systems with multiple 24V accessories.
• Install difficulty: 2/5 — Disconnect all power before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (verify 0V before touching terminals). Label or photograph all wire connections before removal. Reconnect primary (line) wires first, then secondary (24V) wires.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our NationalHVACParts.com warehouse.

Compatibility: Designed for the Carrier C4850C50AJ03061 packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit data plate or transformer label before ordering. If you are unsure of fitment, our HVAC parts specialists can verify compatibility before you purchase. Order today and get same-day shipping on all in-stock OEM parts.