OEM Carrier Transformer 40VA 120V to 24V Control Circuit for Model C48A302551

This is the factory-specified OEM replacement transformer (part number HT01BD236) for the Carrier C48A302551 packaged unit. The transformer steps line voltage (120V) down to 24V to power the entire low-voltage control circuit — including the thermostat, contactor coil, and control board. When this component fails, nothing in the system responds: the thermostat goes blank, the unit won't call for heating or cooling, and there are no error codes because the board itself has lost power.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | Factory OEM part number HT01BD236 | Direct drop-in replacement with matched mounting footprint and lead configuration
• OEM vs Generic: OEM transformers are wound and insulated to Carrier's exact VA and thermal specifications. Undersized or off-tolerance generic units can overheat under peak control-circuit load, blow internal fuses, and damage downstream boards — costing far more than the transformer itself.
• Install difficulty: 2/5 — Disconnect power at the breaker and verify zero voltage with a multimeter before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, wire nuts or spade connectors, and a multimeter to confirm 24V output after installation. Label all wires before removal.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship the same business day from our climate-controlled warehouse.

Compatibility: Designed specifically for the Carrier C48A302551 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. If you're unsure of fitment, our HVAC parts specialists confirm compatibility before your order ships — no guesswork, no returns.