OEM Carrier 40VA Control Transformer for Model C48A502064

This OEM control transformer (part# HT01BD702) is the factory-specified replacement for the Carrier C48A502064 packaged unit. The transformer steps down 120V line voltage to the 24V AC signal required by the thermostat, control board, contactor coil, and all other low-voltage control circuit components. When the transformer fails, the entire control circuit goes dark — the thermostat loses power, the contactor coil cannot energize, and the system will not respond to any call for heating or cooling. A shorted downstream component can also blow the secondary winding, so always inspect fuses and wiring before installing a replacement.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Class 2 insulation | Replaces OEM part# HT01BD702
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact VA and voltage tolerances. Generic transformers often underperform at 40VA load, causing voltage sag that triggers nuisance lockouts and premature control board failures.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after install). Photograph all wiring connections before removing the old unit. Verify no downstream short exists before energizing.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier C48A502064 packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. Our fitment team is available to verify compatibility prior to purchase — contact us before you order if you have any questions.