OEM Carrier Control Transformer 40VA 120V/24V for Model PH4GNXB30000AA

This OEM control transformer (part# HT01BD242) is the factory-specified replacement for the Carrier PH4GNXB30000AA packaged heat pump unit. The transformer steps down line voltage (120V) to the 24V AC control voltage that powers your thermostat, control board, relay coils, and all low-voltage safety circuits. When this component fails, the entire control circuit goes dark — nothing works: the thermostat goes blank, the system will not respond to any call for heating or cooling, and contactors will not energize.

• Specs: Primary: 120V AC | Secondary: 24V AC | 40VA rating | Factory OEM replacement | Terminal block connections for fast drop-in install
• OEM vs Generic: This is a genuine Carrier OEM part (HT01BD242), wound and tested to exact factory tolerances. Generic transformers frequently underperform on VA capacity, causing nuisance lockouts and premature control board failure from voltage sag under load.
• Install difficulty: 2/5 — Always shut off power at the disconnect AND the breaker before beginning. Tools needed: flat-head and Phillips screwdrivers, multimeter, wire nuts or terminal connectors. Photograph all wiring before removal. Verify primary and secondary voltages with a multimeter after install before restoring full power.
• Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our warehouse.

Compatibility: Engineered for the Carrier PH4GNXB30000AA packaged heat pump. Always verify your unit's data plate voltage and VA rating match before ordering. Our technical team is available to confirm fitment — contact us before you order if you have any questions.