OEM Carrier Control Transformer 120V–24V 40VA for Model PG9MAA060140AFKA (HT01BC116 / HT680054)

This OEM control transformer is the factory-specified replacement for the Carrier PG9MAA060140AFKA gas furnace. The transformer steps down 120V line voltage to 24V AC, powering every low-voltage control circuit in the system — including the thermostat, gas valve, control board, and inducer relay. When this part fails, the entire control circuit goes dark: your thermostat displays nothing, the furnace won't respond to calls for heat, and no diagnostic fault codes will appear because the board itself has no power.

• Specs: Input 120V AC | Output 24V AC | 40VA rating | Foot-mount configuration | Wire-lead connections | 60 Hz | Includes 3A inline fuse protection
• OEM vs Generic: OEM transformers are wound to exact Carrier factory VA tolerances, ensuring stable 24V output under full load. Undersized generic units can sag voltage, causing erratic board behavior, nuisance lockouts, or premature control board failure — as confirmed by field technicians.
• Install difficulty: 2/5 — Shut off power at the breaker and verify zero voltage before disconnecting. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Photograph existing wiring before removal. Check C and R terminals on the control board for 24V output after installation to confirm proper operation.
• Warranty & Shipping: 1-year OEM factory warranty. In stock — ships same business day from our warehouse.

Compatibility & Supersession Note: Originally sold as HT01BC116; the current OEM replacement part number is HT680054, which ships in an official Carrier/Bryant factory-authorized parts box and is a direct drop-in. Also replaces HT01BC115, HT01BC120, HT01BB126, HT01CT120, and several additional legacy part numbers. Verify 120V primary input and 24V/40VA output on your unit's wiring diagram before ordering. Questions about fitment? Our HVAC specialists confirm compatibility before you buy.