OEM Carrier 40VA Control Transformer HT01BD236 for Model C4850C48ZN035500

This OEM control transformer (part number HT01BD236) is the factory-specified replacement for the Carrier C4850C48ZN035500 packaged unit. The transformer steps down 120V line voltage to the 24V signal required by your thermostat, control board, contactor coil, and all low-voltage safety circuits. When the transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system won't respond to any command, and nothing turns on. It is often the first component to diagnose when a unit shows zero low-voltage activity.

• Specs: Primary 120V AC | Secondary 24V AC | 40VA rated | OEM part number HT01BD236 | Factory-matched impedance and thermal protection
• OEM vs Generic: This OEM transformer meets exact Carrier factory specifications for VA rating, insulation class, and thermal cutout thresholds. Generic transformers often run undersized VA ratings, causing premature failure or nuisance tripping under normal load — especially in systems with multiple accessories drawing from the 24V circuit.
• Install Difficulty: 2/5 — Shut off all power at the breaker and disconnect switch before starting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire stripper, multimeter to confirm 0V before touching wiring. Label or photograph all low-voltage wiring connections before removal.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier C4850C48ZN035500 packaged unit. Verify your existing transformer's primary/secondary voltage and VA rating on the data plate before ordering. If you have questions about fitment or want us to verify compatibility before you buy, our HVAC parts specialists are standing by. Order today and your part ships same business day.