OEM Carrier 40VA Control Transformer for Model GB1AAV048111AFJA

This is the OEM factory-replacement control transformer (part# HT01BC116) for the Carrier GB1AAV048111AFJA packaged gas/electric unit. The transformer steps down line voltage (120V) to the 24V AC signal that powers your thermostat, control board, and all low-voltage control circuits. When this component fails, the entire control circuit goes dead — the thermostat goes blank, relays stop responding, and the system won't heat or cool regardless of settings. A failed transformer is often mistaken for a bad thermostat or control board, making it one of the first components to test during a no-power diagnostic.

• Specs: 40VA rating | Primary: 120V AC | Secondary: 24V AC | Class 2 low-voltage output | Factory-matched impedance for Carrier GB1AAV048111AFJA control circuits
• OEM vs Generic: OEM transformers (HT01BC116) are wound to exact VA and impedance tolerances required by the Carrier control board. Undersized or off-spec generic units can cause nuisance tripping, undervoltage faults, and premature control board failure.
• Install difficulty: 2/5 — Disconnect power at the breaker before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or quick-connects. Always verify 0V at primary terminals before handling. Swap wiring one lead at a time to avoid miswiring.
• Warranty: 1-year OEM factory warranty. Order by 3 PM local time and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for the Carrier GB1AAV048111AFJA packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the data plate or wiring diagram before ordering. Our HVAC parts specialists are available to confirm fitment — just reach out before you buy. In stock and ready to ship today.