OEM Carrier 40VA Control Transformer for Model C4850C50ZN040200

This OEM control transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C50ZN040200 packaged unit. The transformer steps line voltage (120V or 240V) down to the 24V AC signal that powers your thermostat, control board, contactor coil, and all low-voltage control circuits. When this transformer fails, the entire control system goes dark — the thermostat becomes unresponsive, the system won't start, and no error codes will display because the board itself has no power.

• Specs: 40VA rating | Primary: 120V/240V | Secondary: 24V AC | OEM part number HT01BD236 | Factory-matched for Carrier C4850C50ZN040200 packaged units
• OEM vs Generic: This OEM transformer is wound and insulated to Carrier's exact specifications, ensuring stable 24V output under full control-circuit load. Generic transformers frequently underperform at rated VA, causing nuisance tripping of the internal fuse and intermittent control failures.
• Install difficulty: 3/5 — Disconnect all power before servicing. Tools needed: multimeter, flathead and Phillips screwdrivers, wire stripper, needle-nose pliers. Verify 24V output at secondary terminals after installation. Label all low-voltage wiring before disconnecting and check for a shorted control wire that may have caused the original failure.
• Warranty: 1-year OEM factory warranty against defects. Orders placed before cutoff ship same business day from our climate-controlled warehouse.

Compatibility: Designed for the Carrier C4850C50ZN040200 packaged unit. Verify your existing transformer's VA rating and primary voltage on the unit data plate before ordering — substituting an undersized VA transformer will result in premature failure. If you have questions about fitment, our HVAC parts specialists confirm compatibility before your order ships.