OEM Carrier Transformer 40VA 120V–24V for Model PH13NR042000AAAA

This OEM Carrier transformer (part# HT01AW229) is the factory-specified replacement for the Carrier PH13NR042000AAAA heat pump system. The transformer steps down 120V line voltage to the 24V AC signal that powers your entire control circuit — including the thermostat, contactor coil, and control board. When the transformer fails, the system goes completely unresponsive: the thermostat goes blank, the unit will not energize, and no error codes are displayed because there is no low-voltage power to run any diagnostics.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Factory OEM-matched windings and insulation class | Direct plug-and-play fit for PH13NR042000AAAA
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the factory control board. Generic units often run under-rated VA, causing nuisance tripping of the 3-amp fuse and premature board failure.
• Install Difficulty: 2/5 — Shut off all power to the unit before starting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after install). Label all wires before disconnecting the old transformer.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Designed and factory-matched for the Carrier PH13NR042000AAAA heat pump. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit's data plate or wiring diagram before ordering. Our fitment team is available to confirm compatibility before you buy — same-day shipping on all in-stock orders.