OEM Carrier 40VA Control Transformer HT01BD242 for Model PH4GPXB48000AA

This OEM control transformer (part number HT01BD242) is the factory-specified replacement for the Carrier PH4GPXB48000AA packaged heat pump unit. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coils, and all low-voltage control circuits. When it fails, the entire control system goes dark — the thermostat won't respond, the unit won't energize, and nothing happens on a call for heating or cooling. This is often misdiagnosed as a failed control board, so always test the transformer first with a multimeter before replacing more expensive components.

• Specs: 40VA rating | 120V primary / 24V secondary | Factory-matched OEM replacement | Designed for continuous-duty control circuit service
• OEM vs Generic: This OEM unit is wound to Carrier's exact VA and voltage tolerance specifications. Generic transformers may run under-spec under load, causing intermittent control failures and nuisance lockouts.
• Install Difficulty: 2/5 — Disconnect all power before servicing. Tools needed: flathead and Phillips screwdrivers, wire nuts or spade connectors, multimeter to verify 24V output after installation. Label all wires before disconnecting.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PH4GPXB48000AA packaged heat pump units. Verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate or wiring diagram before ordering. Our HVAC parts specialists are available to confirm fitment — contact us before you buy if you have any questions.