OEM Carrier 40VA Control Transformer for Model C4850C48ZN040500

This OEM control transformer (part# HT01BD236) is the factory-specified replacement for the Carrier C4850C48ZN040500 packaged unit. The transformer steps down 120V line voltage to 24V AC, powering the entire low-voltage control circuit — including the thermostat, contactor coil, and control board. When this component fails, the result is total system unresponsiveness: a blank thermostat, no contactor pull-in, and a unit that won't start regardless of demand. It is one of the most commonly overlooked failure points in a no-heat, no-cool diagnostic.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Class 2 control circuit | Compatible with OEM wiring harness on C4850C48ZN040500
• OEM vs Generic: This is the genuine Carrier OEM part (HT01BD236), manufactured to exact VA and voltage tolerances. Generic transformers may be undersized or use inferior core laminations, causing overheating, premature failure, or nuisance tripped fuses on the control circuit.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 24V output post-install). Label all low-voltage wires before disconnecting. Typical replacement time: 20–30 minutes.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our HVAC parts warehouse.

Compatibility: Engineered for Carrier model C4850C48ZN040500 packaged units. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate before ordering to confirm an exact match. Our parts specialists are available to verify fitment — contact us before you order if you have any questions. Order today and most shipments arrive within 1–2 business days.