OEM Carrier Furnace Transformer 40VA 120V/24V — Model PG9MAB024060ACSA (HT01BC116 / HT680054)

This is the factory-specified OEM step-down transformer for the Carrier PG9MAB024060ACSA gas furnace. The transformer converts 120V line voltage down to 24V AC to power all low-voltage control circuit components — including the thermostat, gas valve, inducer relay, and control board. When this transformer fails, the result is total loss of low-voltage power: a blank thermostat display, no response to any call for heat, and a furnace that appears completely dead despite line voltage being present. A failed transformer can also be caused by a downstream short circuit in the 24V wiring, so always inspect low-voltage wiring before installing the replacement.

• Specs: 40VA rating | 120V primary input | 24V secondary output | 50/60 Hz single-phase | Foot-mount configuration | Wire lead connections with insulated female quick-connects
• OEM vs Generic: This OEM unit is wound to factory-exact VA and voltage tolerances. Generic transformers often run outside ±5% tolerance, which can starve sensitive control boards of proper voltage and cause nuisance lockouts or premature board failure.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdriver, needle-nose pliers, multimeter. Before disconnecting wires, photograph or label all lead connections. After installation, verify 24V output between the R and C terminals on the control board before restoring full power.
• Warranty & Shipping: 1-year OEM manufacturer warranty. In stock — ships same business day from our warehouse when ordered by 3 PM local time.

Compatibility & Part Number Note: OEM part number HT01BC116 has been superseded by HT680054 — the current factory-authorized replacement shipped in a Carrier factory parts box. This listing fulfills orders originally placed under HT01BC116. Fits Carrier PG9MAB024060ACSA and other Carrier, Bryant, and Payne furnace models using a 40VA 120V/24V transformer. Verify your existing transformer's VA and voltage ratings on its label before ordering. Questions about fitment? Our HVAC parts team confirms compatibility before you buy — reach out anytime.