OEM Carrier Control Transformer 40VA 120V–24V for Model PH4GEXB48000AA

This OEM replacement transformer (part number HT01BD242) is the factory-specified control transformer for the Carrier PH4GEXB48000AA packaged HVAC unit. The transformer steps down 120V line voltage to 24V AC to power the entire low-voltage control circuit — including the thermostat, contactor coil, and control board. When the transformer fails, the result is a completely unresponsive system: the thermostat goes dark, the unit won't call for heating or cooling, and no fault codes are generated because the board itself has no power to display them.

• Specs: 40VA output rating | 120V primary / 24V secondary | Matches factory-original wiring configuration and mounting footprint for PH4GEXB48000AA
• OEM vs Generic: This is the genuine Carrier OEM part (HT01BD242), manufactured to exact VA and voltage tolerances. Generic transformers can deliver inconsistent 24V output, causing nuisance lockouts, erratic thermostat behavior, and 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 (verify 0V before touching terminals). Label or photograph all low-voltage wiring before disconnecting. Reconnect primary (line) wires last.
• Warranty: 1-year OEM factory warranty against defects. In-stock units ship same business day from our warehouse when ordered before 3 PM local time.

Compatibility: Designed and verified for Carrier model PH4GEXB48000AA packaged units. Always confirm the VA rating and primary/secondary voltages on your unit's data plate or wiring diagram before ordering. Our HVAC parts specialists are available to confirm fitment — reach out before you order if you have any questions.