OEM Carrier 40VA Control Transformer 120V–24V for Model GB1AAV024045AGJA

This OEM replacement transformer (part# HT01CN001) is the factory-specified control circuit transformer for the Carrier GB1AAV024045AGJA gas furnace. Its job is to step down 120V line voltage to the 24V AC signal that powers your thermostat, control board, gas valve, and all low-voltage safety circuits. When this transformer fails, the entire control system goes dark — the thermostat loses power, the furnace will not attempt ignition, and nothing responds. It is one of the first components to check when a furnace shows zero activity at the thermostat.

• Specs: 40VA rated | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01CN001 | Factory-matched impedance and thermal protection
• OEM vs Generic: This OEM unit includes the factory-spec thermal cutoff and tight voltage regulation required by the Carrier control board. Generic transformers frequently output slightly elevated voltages that can damage sensitive solid-state boards over time.
• Install difficulty: 2/5 — Shut off power at the breaker and confirm zero voltage with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Label or photograph all wiring connections before disconnecting. Typical swap time is 15–30 minutes for a competent DIYer.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our climate-controlled warehouse.

Compatibility: Engineered specifically for the Carrier GB1AAV024045AGJA gas furnace. Always verify the 120V primary / 24V secondary 40VA rating against your unit's data plate before ordering. If you have any fitment questions, our HVAC parts specialists confirm compatibility before your order ships — no guesswork required.