OEM Carrier Control Transformer 40VA for Model C4850C50AJ03051

This OEM step-down transformer is the factory-specified replacement for the Carrier C4850C50AJ03051 packaged unit. The control transformer converts 120V line voltage down to the 24V signal used by your thermostat, contactor coil, and control board. When it fails, the entire low-voltage control circuit goes dead — the thermostat goes blank, the system stops responding to calls for heating or cooling, and no components energize. OEM part number HT01BD236.

• Specs: 120V primary | 24V secondary | 40VA rated | Factory-matched windings and insulation class | Matches original mounting footprint
• OEM vs Generic: This OEM transformer (HT01BD236) is wound to Carrier's exact VA rating and insulation spec. Undersized or off-brand transformers can overheat under normal control circuit load, tripping internal breakers or failing prematurely — especially in systems with multiple accessories drawing 24V power.
• Install difficulty: 2/5 — Shut off power at the disconnect and confirm with a multimeter before touching any wiring. Tools needed: flat-head and Phillips screwdrivers, wire stripper, multimeter, needle-nose pliers. Photograph all wiring connections before removal. The transformer typically mounts to the control panel with two screws and connects via spade or screw terminals.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier C4850C50AJ03051 packaged unit. Verify your existing transformer's primary voltage (120V), secondary voltage (24V), and VA rating on the unit data plate or transformer label before ordering. If your system powers multiple 24V accessories (humidifiers, UV lights, zone boards), confirm total VA draw does not exceed 40VA. Our team is available to verify fitment before you order — don't guess on a control circuit component.