OEM Carrier 40VA Control Transformer 120V–24V for Model PG8JAA048070AAJA

This OEM Carrier control transformer is the factory-specified replacement for the Carrier PG8JAA048070AAJA gas furnace. The transformer steps down 120V AC line voltage to the 24V AC signal required to power the thermostat, control board, gas valve, and all low-voltage safety circuits. When it fails, the entire low-voltage control circuit goes dead — the thermostat goes blank, the system refuses to call for heat, and no fault codes are displayed because there is no power to display them. A failed transformer is a common and often misdiagnosed cause of a completely unresponsive furnace.

• Specs: 40VA rating | 120V AC primary input | 24V AC secondary output | 60 Hz | Foot-mount configuration | Wire lead connections | Part# HT01BC116 (superseded by HT680054)
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the Carrier control board. Undersized or out-of-tolerance generic transformers can overdraw current, trip thermal fuses, or cause erratic control board behavior — often leading to a second unnecessary repair call.
• Install difficulty: 2/5 — Always shut off power at the breaker and gas supply before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 0V before touching wiring). Photograph all wire connections before disconnecting. The transformer mounts via a foot bracket and connects via wire leads — a straightforward swap for any experienced DIYer or technician.
• Warranty: 1-year OEM factory warranty on parts. Ships same business day from our warehouse when ordered before 3 PM local time.

Compatibility: Engineered as a direct OEM replacement for Carrier model PG8JAA048070AAJA gas furnaces. Note that OEM part number HT01BC116 has been superseded by updated part number HT680054 — both are the same specification and either number is acceptable for ordering. Cross-references include HT01BC115, HT01BC116B, HT01BC120, HT01BB126, and HT680054. Verify your unit's data plate voltage requirements before ordering. Questions about fitment? Our HVAC parts specialists verify compatibility before you order — no guesswork.