OEM Carrier 40VA Control Transformer 120V–24V for Model PG8MAA066135ADJA (HT01BC116)

This OEM Carrier control transformer is the factory-specified replacement for the Carrier PG8MAA066135ADJA gas furnace. The transformer steps down 120V line voltage to the 24V AC signal required to power the thermostat circuit, gas valve, contactor coil, and all low-voltage controls throughout the system. When this transformer fails, nothing works — the thermostat goes blank, the furnace won't fire, and the entire control circuit goes dead. It is one of the first components to check when a furnace has completely stopped responding.

• Specs: 40VA rating | 120V AC primary input | 24V AC secondary output | 60 Hz | Foot-mount configuration | OEM part number HT01BC116 (superseded by HT680054)
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances. Undersized or off-spec generic transformers can sag under full load, causing intermittent lockouts, nuisance tripped fuses, and premature failure of the gas valve or control board.
• Install Difficulty: 2/5 — Shut off power at the breaker before starting. Photograph all wiring connections before disconnecting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after install). Always check for a shorted low-voltage wire before replacing — a short is the most common cause of transformer burnout.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier PG8MAA066135ADJA gas furnace. Also supersedes part numbers HT01BC115, HT01BB126, HT01CT120, HT01BC120, HT01AW115, and HT01AA012. Verify your unit's data plate lists a 40VA / 120–24V transformer specification before ordering. Need help confirming fitment? Our HVAC parts team verifies compatibility before you order — contact us today and ship the same day.