OEM Carrier Furnace Transformer 120V–24V 40VA for Model PG8UAA042091ABJA

This OEM step-down transformer is the factory-specified replacement for the Carrier PG8UAA042091ABJA gas furnace. The transformer converts 120V line voltage to 24V AC to power the furnace's entire low-voltage control circuit — including the thermostat, control board, gas valve, and zone controls. When this part fails, nothing in the furnace responds: no ignition attempt, no blower, no call-for-heat reaction. If you measure 0V between the R and C terminals on your control board, a failed transformer is the first thing to replace.

• Specs: Primary voltage: 120V AC | Secondary voltage: 24V AC | VA rating: 40VA | Frequency: 60 Hz | Single phase | Foot-mount configuration | Wire lead connections with insulated female quick-connect terminals
• OEM vs Generic: This OEM transformer is built to exact Carrier factory tolerances. Generic transformers frequently use lighter-gauge windings and lower-rated cores that run hot, blow fuses prematurely, or fail to sustain the 24V output under full system load — especially with multi-zone setups or added accessories.
• Install difficulty: 2/5 — Shut off all power to the furnace at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Photograph all wiring connections before disconnecting. Mount the new transformer to the existing bracket and reconnect leads to matching terminals. Verify 24V output at R–C before closing the cabinet.
• Warranty: 1-year OEM manufacturer warranty. In stock — ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PG8UAA042091ABJA gas furnace. This part supersedes and replaces original part number HT01BC116, as well as HT01BC115, HT01BB126, HT01CT120, HT01BC120, and several other legacy Carrier/Bryant transformer part numbers. Verify your unit's data plate shows a 120V primary supply before ordering. Have questions about fitment? Our HVAC parts specialists confirm compatibility before you buy — order with confidence and get same-day shipping.