OEM Carrier 40VA Control Transformer HT01BD242 for Model PH3GNA048000AB

This OEM control transformer (part# HT01BD242) is the factory-specified replacement for the Carrier PH3GNA048000AB packaged heat pump unit. The transformer steps down the 120V line voltage to the 24V signal required by your thermostat, control board, and all low-voltage switching circuits. When it fails, the entire control circuit goes dark — the thermostat loses power, the system stops responding to calls for heating or cooling, and you may find a blown fuse on the control board caused by a shorted secondary winding.

• Specs: 120V primary input | 24V secondary output | 40VA rating | Direct OEM replacement for part# HT01BD242 | Factory-matched impedance and insulation class
• OEM vs Generic: This is a genuine OEM Carrier transformer wound to exact factory specification. Generic aftermarket transformers frequently underperform on VA capacity, leading to nuisance fuse failures and premature secondary winding burnout — especially in systems with multiple 24V accessories.
• Install difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, 1/4" nut driver, multimeter. Verify 0V on both primary and secondary terminals before disconnecting. Label all wiring or photograph before removal. The transformer mounts to the control panel bracket with two screws; swap wire-for-wire on both primary and secondary terminals.
• Warranty: 1-year OEM factory warranty. In-stock units ship same business day from our warehouse.

Compatibility: Designed specifically for the Carrier PH3GNA048000AB packaged heat pump unit (4-ton, R-410A). Always confirm the VA rating and voltage on your unit's data plate before ordering. Not sure if this part fits your exact configuration? Our HVAC parts specialists verify fitment before you order — contact us anytime.