OEM Carrier Control Transformer 40VA 120V/24V for Model GB3AAV036075AAJA

This OEM replacement transformer (part number HT01BC116) is the factory-specified control transformer for the Carrier GB3AAV036075AAJA gas furnace. The transformer steps down line voltage from 120V to 24V AC, powering the entire low-voltage control circuit — including the thermostat, gas valve, inducer relay, and ignition control board. When this transformer fails, absolutely nothing responds: the thermostat goes blank, the furnace won't attempt ignition, and no error codes are generated because the control board itself has no power. A failed transformer is often misdiagnosed as a bad control board, so always test it first with a multimeter before replacing more expensive components.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | Class 2 control transformer | Direct OEM replacement for part number HT01BC116
• OEM vs Generic: This factory OEM unit is wound to exact VA and voltage tolerances. Undersized or off-spec generic transformers can overheat, trip their internal fuse, or deliver insufficient current to hold contactors and gas valves open — causing intermittent lockouts that are extremely difficult to diagnose.
• Install difficulty: 2/5 — Disconnect power at the breaker before starting. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Label or photograph all low-voltage wiring connections before removing the old unit. The transformer mounts with one or two screws inside the blower compartment.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our stocked warehouse.

Compatibility: Designed for the Carrier GB3AAV036075AAJA 80% AFUE gas furnace. Verify your existing transformer's VA rating and primary/secondary voltages on the data plate or wiring diagram before ordering. If your unit has a blown transformer fuse or repeatedly fails transformers, inspect for shorted low-voltage wiring before installing the new unit. Questions about fitment? Our HVAC parts specialists confirm compatibility before you buy.