OEM Carrier 40VA Control Transformer for Model C4850C50AY02551

This is the OEM factory-replacement control transformer (part# HT01BD236) for the Carrier C4850C50AY02551 packaged unit. The transformer steps down 120V line voltage to 24V, powering the entire low-voltage control circuit — including the thermostat, contactor coil, and control board. When this transformer fails, nothing in your system responds: the thermostat goes blank, the unit won't call for heating or cooling, and the system appears completely dead. A failed transformer is often caused by a shorted control wire, a failed component drawing excess current, or simply age-related winding breakdown.

• Specs: 40VA rated | 120V primary → 24V secondary | Direct OEM replacement | Part number HT01BD236 | Factory-matched winding impedance and thermal protection
• OEM vs Generic: OEM transformers are wound to exact VA and impedance specs for the Carrier C4850C50AY02551 control circuit. Generic units often under-deliver on VA capacity, causing nuisance tripping, brownouts on the 24V circuit, and premature contactor coil failure.
• Install difficulty: 2/5 — Shut off all power before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output after install and to locate any downstream short before replacing). Always identify and correct the root cause of transformer failure before installing the new unit.
• Warranty: 1-year OEM factory warranty against defects. Orders placed by 3PM local time ship same business day from our stocked warehouse.

Compatibility: Designed specifically for the Carrier C4850C50AY02551 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering. If you're unsure of fitment, our HVAC parts specialists confirm compatibility before your order ships — no guesswork required.