OEM Carrier Control Circuit Transformer 40VA for Model C4850C48ZN055200

This is the factory OEM replacement transformer (part # HT01BD236) for the Carrier C4850C48ZN055200 packaged unit. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and all low-voltage safety circuits. When it fails, the entire control circuit goes dark — the thermostat goes blank, no relays click, and the system will not respond to any call for heating or cooling. A failed transformer is often misdiagnosed as a control board failure, making this an essential first diagnostic replacement.

• Specs: 40VA rating | 120V primary / 24V secondary | Ring-type or foot-mount bracket | OEM part number HT01BD236 | Factory-matched output tolerance for stable low-voltage control
• OEM vs Generic: The OEM HT01BD236 transformer is wound to exact VA and voltage tolerances required by the Carrier C4850C48ZN055200 control board. Generic transformers with loose VA ratings can cause erratic low-voltage behavior, nuisance tripping of the 3A fuse, or premature control board failure.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, needle-nose pliers, multimeter (to confirm 24V output after install). Note and photograph all wire connections before removal. Check and replace the low-voltage fuse if the original transformer failed due to a short.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our climate-controlled warehouse.

Compatibility: Designed specifically for the Carrier C4850C48ZN055200 packaged unit. Verify primary voltage (120V) and VA rating on your unit's data plate before ordering. If you're unsure of fitment, our HVAC parts specialists can confirm compatibility before you buy — same-day shipping on all in-stock orders placed before 3PM local time.