OEM Carrier 40VA Control Transformer for Model GB1AAV042091ABJA

This OEM control transformer (part# HT01BC116) is the factory-specified replacement for the Carrier GB1AAV042091ABJA gas furnace. The transformer steps down 120V line voltage to the 24V signal voltage required by your thermostat, control board, gas valve, and all low-voltage control components. When the transformer fails, the entire low-voltage control circuit goes dead — the thermostat goes blank, nothing responds to a call for heat, and the system will not attempt ignition. A blown fuse on the secondary side is often the first warning sign before full transformer failure.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | Class 2 transformer | OEM part number HT01BC116 | Factory-matched construction for direct drop-in fit
• OEM vs Generic: This factory OEM transformer is wound to exact VA and voltage tolerances for the GB1AAV042091ABJA control circuit. Generic transformers frequently run under-rated VA, causing overheating, nuisance fuse failures, and premature control board damage — costing far more in downstream repairs.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter to verify 24V output after installation. Label or photograph all wiring connections before removal. Secondary circuit fuse should be inspected and replaced if blown.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our warehouse when ordered before 3PM local time.

Compatibility: Designed for the Carrier GB1AAV042091ABJA gas furnace. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. If you're unsure, our HVAC parts specialists confirm fitment before you buy — no guesswork, no returns.