OEM Carrier Furnace Transformer 120V–24V 40VA for Model PG8MAA066110AAJA

This OEM step-down transformer is the factory-specified replacement for the Carrier PG8MAA066110AAJA gas furnace. The transformer converts 120V line voltage down to 24V AC to power the low-voltage control circuit — including the thermostat, control board, gas valve, and all 24V safety switches. When this transformer fails, the entire control circuit goes dead: the thermostat goes blank, the furnace won't respond to calls for heat, and the control board shows no activity. It is one of the first components to check when a furnace is completely unresponsive.

• Specs: 120V primary | 24V secondary | 40VA rating | 60Hz single-phase | Foot-mount configuration | Wire lead connections with insulated female quick-connects
• OEM Part Numbers: Replaces HT01BC116 (original) and current OEM successor HT680054. Cross-references: HT01BC115, HT01BB126, HT01CT120, HT01BC120, HT01AW115, B1810113, 322666-701
• OEM vs Generic: This OEM unit is factory-matched to Carrier's exact VA rating and mounting footprint. Generic transformers are often undersized in VA capacity or mount incorrectly, risking overload, nuisance tripping of the furnace's internal fuse, or shortened service life.
• Install difficulty: 2/5 — Shut off power to the furnace at the disconnect switch before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Photograph all low-voltage wiring before disconnecting. Check and replace the low-voltage fuse on the control board at the same time — a shorted thermostat wire is the most common cause of transformer failure.
• Warranty: 1-year OEM manufacturer's warranty. In stock — ships same business day from our warehouse.

Compatibility: Engineered for the Carrier PG8MAA066110AAJA gas furnace. Also compatible with a wide range of Carrier, Bryant, and Payne furnaces requiring a 120V–24V 40VA foot-mount transformer. Verify your unit's control voltage and VA requirements on the data label inside the furnace cabinet before ordering. Have questions? Our HVAC parts specialists verify fitment before you buy — contact us anytime.