OEM Carrier 40VA Control Transformer 120V–24V for Model PG8MAA036045ACJA

This is the factory-specified OEM replacement control transformer for the Carrier PG8MAA036045ACJA gas furnace. The transformer steps down 120V line voltage to the 24V AC signal required to power your thermostat, gas valve, control board, and all low-voltage safety circuits. When this transformer fails, the entire control circuit goes dark — symptoms include a completely blank thermostat display, no response to heat calls, and a furnace that won't attempt ignition despite having power at the unit.

• Specs: 40VA rating | 120V AC primary | 24V AC secondary | 60 Hz | Foot-mount configuration | Wire lead connections | Factory OEM part HT01BC116 (superseded by HT680054)
• OEM vs Generic: OEM transformers are wound and potted to exact VA tolerances, protecting downstream low-voltage components. Aftermarket units frequently deliver unstable secondary voltage, causing nuisance lockouts, control board damage, or premature gas valve failure.
• Install difficulty: 2/5 — Shut off all power to the furnace before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter to verify 24V output after install. Label all wire leads before disconnecting the old transformer. A blown fuse on the control board often accompanies transformer failure — inspect and replace as needed.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for the Carrier PG8MAA036045ACJA gas furnace. Also replaces cross-reference part numbers HT680054, HT01BC115, HT01BB126, HT01BC120, and HT01AW115 across the Carrier, Bryant, and Payne furnace family. Always verify your existing transformer's primary/secondary voltage and VA rating from the data plate before ordering. Our fitment team is available to confirm compatibility before you buy.