OEM Carrier 40VA Control Transformer HT01BC116 for Model GB3AAV048115ACJA

This OEM replacement control transformer (part# HT01BC116) is the factory-specified unit for the Carrier GB3AAV048115ACJA gas furnace. The transformer steps down 120V line voltage to the 24V signal required by your thermostat, control board, contactor coil, and all low-voltage control circuits. When this component fails, the entire control system goes dark — your thermostat shows no power, the furnace won't respond to calls for heat, and diagnostic LED codes may not appear at all. A failed transformer is often misdiagnosed as a bad control board, making this an essential first step in any no-power troubleshooting sequence.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Matches OEM footprint and terminal configuration for direct drop-in replacement
• OEM vs Generic: This factory OEM transformer (HT01BC116) is wound to exact VA and voltage tolerances required by the Carrier GB3AAV048115ACJA control circuit. Generic transformers frequently run undervoltage under load, causing nuisance lockouts, erratic thermostat behavior, and premature contactor coil failure.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Verify 24V output at secondary terminals after installation before restoring full system power. Always check for a shorted low-voltage wire that may have caused the original failure.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed specifically for the Carrier GB3AAV048115ACJA gas furnace. Verify your existing transformer's VA rating and primary/secondary voltages on the data plate before ordering. If you're unsure of fitment, our parts specialists confirm compatibility before you buy — no guesswork, no return hassle.