OEM Carrier 40VA Control Transformer for Model C4850C50Z3040900

This OEM control transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C50Z3040900 packaged unit. The transformer steps down line voltage from 120V to the 24V signal voltage that powers your thermostat, control board, contactor coil, and all low-voltage safety circuits. When this component fails, the entire control circuit goes dead — the thermostat goes blank, the system won't respond to any call for heating or cooling, and no diagnostic LEDs will illuminate on the control board.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | Factory-matched impedance and thermal protection | OEM part number HT01BD236
• OEM vs Generic: This is the genuine Carrier OEM transformer, wound and rated to exact factory specifications. Generic transformers frequently underperform their stated VA rating, causing nuisance tripping of the internal thermal cutout and premature failure under normal system load.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter (to confirm 0V before touching wiring). Label or photograph all low-voltage wiring connections prior to removal. Incorrect polarity on reinstall can damage the control board.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. Ships same business day from our stocked warehouse.

Compatibility: Designed for the Carrier C4850C50Z3040900 packaged unit. Verify primary voltage, secondary voltage, and VA rating against your unit's data plate and wiring diagram before ordering. Not sure it fits? Our HVAC parts specialists confirm fitment before you purchase — no guesswork, no returns. Order today and your part ships the same business day.