OEM Carrier 40VA Control Transformer 120V/24V for Model PH12NA042000AGAA

This OEM control transformer (part #HT01AW229) is the factory-specified replacement for the Carrier PH12NA042000AGAA packaged heat pump unit. The transformer steps down 120V line voltage to the 24V used by the low-voltage control circuit — powering your thermostat, contactor coil, reversing valve, and safety switches. When this transformer fails, the entire control circuit goes dead: the thermostat goes blank, the system makes no response to any call for heating or cooling, and no safety fault codes are generated because the board itself has lost power.

• Specs: Input: 120V AC | Output: 24V AC | VA Rating: 40VA | Factory OEM part #HT01AW229 | Direct plug-in replacement with original wiring harness connectors
• OEM vs Generic: The OEM HT01AW229 transformer is wound and rated to exact Carrier factory specifications, ensuring precise 24V output under full VA load. Generic transformers often use thinner windings that sag under peak current draw, causing nuisance lockouts and board voltage instability.
• Install Difficulty: 2/5 — Shut off all power to the unit before servicing. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (verify 0V before touching terminals). Label all low-voltage wires before disconnecting. Recheck output voltage after installation before re-energizing the full system.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships the same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PH12NA042000AGAA packaged heat pump. Verify primary input voltage and VA rating on your unit's data plate before ordering. Our fitment team is available to confirm compatibility — reach out before you order if you have any questions.