OEM Carrier Transformer 40VA 120V to 24V for Model M150039MX41011526

This is the factory OEM replacement transformer (part number HT01BD118) for the Carrier M150039MX41011526. The transformer steps down line voltage from 120V to 24V to power the low-voltage control circuit — including the thermostat, contactor coil, and control board. When this component fails, the entire control circuit goes dead: the thermostat display may go blank, the system may refuse to respond to any call for heating or cooling, and no components will energize. It is often one of the first parts to inspect when a system appears completely unresponsive.

• Specs: 40VA rating | 120V primary input | 24V secondary output | OEM part number HT01BD118 | Factory-matched construction for reliable low-voltage signal delivery
• OEM vs Generic: This OEM transformer is wound and rated to Carrier factory specifications, ensuring stable 24V output under full control circuit load. Generic transformers may be undersized in VA rating, causing overheating, nuisance tripping of the internal fuse, and premature failure — particularly in systems with multiple low-voltage accessories.
• Install difficulty: 2/5 — Always shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after installation). Label or photograph all low-voltage wiring before disconnecting from terminals.
• Warranty: 1-year OEM factory warranty against defects. In-stock units ship same business day when ordered before cutoff.

Compatibility: Designed as a direct OEM replacement for the Carrier M150039MX41011526. Always verify your unit's control circuit voltage and VA requirement on the data plate before ordering. Our HVAC parts specialists are available to confirm fitment — reach out before you order if you have any questions.