OEM Carrier Transformer 120V-24V 40VA for Model PG8MAA042090AAJA (HT01BC116 / HT680054)

This is the factory-specified OEM step-down transformer for the Carrier PG8MAA042090AAJA gas furnace. The transformer converts 120V line voltage to 24V AC to power all low-voltage control circuit components — including the thermostat, control board, gas valve, and inducer relay. When this transformer fails, the entire control circuit goes dark: the thermostat loses power, the furnace will not respond to any call for heat, and nothing works. A failed transformer is often confirmed by checking voltage across the C and R terminals on the control board — a reading of 0V with line power present is a strong indicator of transformer failure.

• Specs: Input 120V AC | Output 24V AC | 40VA rating | Wire lead connections | Foot-mount configuration | 60 Hz
• OEM vs Generic: This OEM unit is factory-matched to exact VA rating and mounting dimensions for the PG8MAA042090AAJA. Generic transformers are frequently reported to have mounting incompatibilities and may run at marginal VA ratings, risking premature failure of downstream low-voltage components.
• Install Difficulty: 2/5 — Shut off power at the breaker and confirm zero voltage before disconnecting any wires. Photograph all wire connections before removal. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Note: HT01BC116 has been superseded by OEM part number HT680054 — this listing ships the current OEM equivalent.
• Warranty: 1-year OEM manufacturer warranty. In-stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier PG8MAA042090AAJA gas furnaces. Also cross-references Bryant and Payne models using HT01BC116, HT01BC115, HT01BC120, HT01BB126, HT680054, and related superseded part numbers. Always verify your unit's data plate and existing transformer specs (voltage in/out, VA rating) before ordering. Have a question about fitment? Our HVAC parts team confirms compatibility before you buy — order with confidence.