OEM Carrier Control Circuit Transformer 40VA for Model C4850C48ZG055600

This OEM replacement transformer (part number HT01BD236) is the factory-specified step-down transformer for the Carrier C4850C48ZG055600 packaged unit. Its job is to convert 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and every other low-voltage component in the system. When this transformer fails, absolutely nothing in your control circuit will respond — the thermostat goes dark, the system won't call for heating or cooling, and no fault codes will even appear because there's no power to generate them.

• Specs: 40VA rated | 120V primary / 24V secondary | OEM part number HT01BD236 | Factory-matched output tolerance for stable control-circuit voltage
• OEM vs Generic: OEM transformers are wound to exact VA and voltage specifications. Undersized or off-tolerance generic units can cause nuisance tripping, premature control board failure, or erratic thermostat behavior — especially under peak demand when the contactor coil draws full current.
• Install difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (verify 0V before touching terminals). Note wire colors and terminal positions before disconnecting the old unit. Reconnect primary (line voltage) leads first, then secondary (24V) leads.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Engineered specifically for the Carrier C4850C48ZG055600 packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit's data plate or original transformer label before ordering. Need help verifying fitment? Our HVAC parts team will confirm compatibility before you buy — just reach out before placing your order.