OEM Carrier 40VA Control Transformer for Model C4850C50Z3040200

This OEM control transformer (part number HT01BD236) is the factory-specified replacement for the Carrier C4850C50Z3040200 packaged unit. The transformer steps down 120V line voltage to the 24V signal needed to power the control board, thermostat, contactor coil, and all low-voltage safety circuits. When this part fails, absolutely nothing responds — the thermostat goes dark, the system won't call for heating or cooling, and no error codes are generated because the control circuit has no power to report them.

• Specs: 40VA rated | 120V primary / 24V secondary | Class 2 insulation | Direct OEM replacement for part number HT01BD236 | Mounts to existing bracket with standard wiring harness connections
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the Carrier control board. Undersized or off-tolerance generic units overheat under load, blow fuses repeatedly, and can damage downstream boards — a far more expensive repair.
• Install difficulty: 2/5 — Shut off all power to the unit at the disconnect before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter, needle-nose pliers. Label and photograph all low-voltage wiring connections before removing the old transformer. Verify 24V output at secondary terminals before closing the panel.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. Ships same business day from our climate-controlled warehouse.

Compatibility: Engineered for the Carrier C4850C50Z3040200 packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. If you're unsure of fitment, our HVAC parts specialists verify compatibility before your order ships — no guesswork required.