OEM Carrier Furnace Transformer 40VA 120V to 24V — HT01CN001 for Model UPFLOW125FAUHAC14B

The Carrier HT01CN001 is the factory-specified control circuit transformer for the UPFLOW125FAUHAC14B upflow gas furnace. Its job is to step line voltage down from 120V to a safe 24V DC that powers the thermostat, control board, gas valve relay, and every other low-voltage component in the system. When this transformer fails — typically from an electrical surge, a short in the control wiring, or years of normal wear — the entire 24V control circuit goes dead: the thermostat goes blank, the furnace refuses to respond to any command, and you may hear a faint buzz or hum from the transformer housing itself.

• Specs: 120V primary | 12V / 24V secondary | 40VA rated | OEM part number HT01CN001 | Replaces legacy part numbers HT01BJ115, 19EA41612, 19EA42612
• OEM vs Generic: This is a genuine Carrier Factory Authorized Part — not an aftermarket substitute. OEM transformers are wound and potted to exact VA and impedance tolerances, ensuring stable 24V output under full control-circuit load. Generic units often underperform at VA limits, leading to nuisance lockouts and premature control board damage.
• Install difficulty: 3/5 — Shut off power at the disconnect AND the breaker before beginning. Tools needed: multimeter (verify zero voltage before touching terminals), flat-head and Phillips screwdrivers, needle-nose pliers, wire nuts or push-in connectors. Photograph all low-voltage wiring connections before disconnecting. Check control wiring for shorts before powering up the new transformer — an unresolved short will blow the new unit immediately.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before cutoff.

Compatibility: Factory-matched for Carrier model UPFLOW125FAUHAC14B upflow gas furnace. Verify primary voltage (120V) and VA rating (40VA) on your unit's data plate before ordering. If your furnace uses a 208V or 240V primary, a different transformer part number is required — contact our team to confirm fitment before placing your order.