OEM Carrier Transformer 40VA 120V to 24V for Model M150039MX41011522

This OEM Carrier control circuit transformer (part number HT01BD118) is the factory-specified replacement for the Carrier M150039MX41011522. The transformer steps down 120V line voltage to the 24V signal voltage required to power the control board, thermostat, and all low-voltage safety circuits. When this component fails, the entire control circuit goes dead — the thermostat displays nothing, the system refuses to respond to any call for heating or cooling, and no fault codes appear because the board itself has no power to generate them.

• Specs: 40VA rated | 120V primary input | 24V secondary output | Class 2 transformer | Terminals designed for quick-connect or screw-terminal wiring
• OEM vs Generic: OEM part HT01BD118 is manufactured to Carrier's exact VA rating and insulation class, ensuring stable 24V output under full control circuit load. Off-brand transformers often run undersized, causing voltage sag that triggers nuisance lockouts and premature board failure.
• Install difficulty: 2/5 — Always disconnect power at the disconnect box and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output after install), wire stripper. Label or photograph all wiring connections before removal.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed as the direct OEM replacement transformer for Carrier model M150039MX41011522. Always verify your unit's control circuit voltage requirements on the data plate before ordering. Not sure it fits? Our HVAC parts specialists confirm fitment before you buy — no guesswork required.