OEM Carrier Control Transformer 40VA 120V/24V for Model C48A303564

This is the factory OEM replacement control transformer (part number HT01BD702) for the Carrier C48A303564 packaged unit. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and every other low-voltage component in the system. When the transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system refuses to respond to any call for heating or cooling, and no safety controls can operate. It is often the first component to inspect when a system appears completely unresponsive despite having line voltage present.

• Specs: 40VA rating | 120V primary / 24V secondary | Class 2 insulation | Factory-matched to Carrier C48A303564 control circuit load requirements
• OEM vs Generic: OEM part HT01BD702 is wound to Carrier's exact VA and impedance specifications, ensuring stable 24V output under full control-circuit load. Generic transformers may sag voltage under load, causing intermittent lockouts, nuisance tripping, or premature contactor coil failure.
• 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 verify 24V output after install). Label or photograph all low-voltage wiring before disconnecting from the secondary terminals.
• Warranty: 1-year OEM factory warranty. Orders placed by 3 PM local time ship same business day from our climate-controlled warehouse.

Compatibility: Designed specifically for the Carrier C48A303564 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate or wiring diagram before ordering. If you are unsure of fitment, our HVAC parts specialists are available to confirm compatibility before you purchase — no guesswork required.