OEM Carrier 40VA Control Transformer HT01BD702 for Model C48A502564

This is the factory OEM replacement control transformer (part# HT01BD702) for the Carrier C48A502564 packaged unit. The transformer steps line voltage (120V) down to 24V AC to power the control board, thermostat, contactor coil, and all low-voltage safety circuits. When this transformer fails, the entire control circuit goes dark — the thermostat shows no response, the system won't call for heating or cooling, and the contactor will not energize. It is often the first component to inspect when nothing in the system responds at all.

• Specs: 40VA output | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01BD702 | Factory-matched for Carrier C48A502564 packaged units
• OEM vs Generic: OEM transformers are wound and insulated to Carrier's exact VA rating and thermal specs. Undersized or off-brand transformers can overheat under combined low-voltage load and trip internal protection — or fail entirely within one season.
• Install difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output after install), wire nuts or spade connectors. Photograph all wiring connections before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier C48A502564 packaged unit. Verify primary and secondary voltage ratings on your unit's data plate and existing transformer label before ordering. If you're unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you purchase — same-day shipping on all in-stock orders.