OEM Carrier Control Transformer 40VA for Model C4850C48AY03051

This OEM control transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C48AY03051 packaged unit. The transformer steps down 120V line voltage to the 24V signal voltage that powers your thermostat, contactor coil, gas valve, and every other low-voltage control circuit in the system. When it fails, the entire control circuit goes dead — your thermostat goes blank, nothing responds to a call for heating or cooling, and no fault codes appear because the board itself has no power.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | OEM part number HT01BD236 | Factory-matched to Carrier C4850C48AY03051 wiring and mounting configuration
• OEM vs Generic: This is the genuine OEM Carrier transformer engineered to exact VA and voltage specifications. Generic transformers often run undersized VA ratings that sag under full control-circuit load, causing intermittent lockouts, nuisance trips, and premature contactor coil failure.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flat-head and Phillips screwdrivers, needle-nose pliers, wire nuts or spade connectors, non-contact voltage tester. Photograph all wiring connections before removal. Confirm primary and secondary leads are correctly landed before restoring power.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our stocked warehouse when ordered before cutoff.

Compatibility: Engineered specifically for the Carrier C4850C48AY03051 packaged unit. Verify your existing transformer's VA rating, primary voltage, and secondary voltage on the unit data plate or existing component label before ordering. If you are unsure of fit, our HVAC parts specialists will confirm compatibility before your order ships — no guesswork required.