OEM Carrier Furnace Transformer 40VA 120V to 24V for Model U19X125U48A

The Carrier HT01CN001 is the factory-specified control circuit transformer for the U19X125U48A HVAC unit. It steps down 120V line voltage to a safe 12/24V output at 40VA — powering the low-voltage control circuit that drives your thermostat, contactor coils, and safety switches. When this transformer fails, the entire control circuit goes dark: the thermostat loses power, the system will not respond to any call for heating or cooling, and you may detect a faint burning smell or buzzing from the transformer housing. Electrical surges and shorted control wiring are the most common causes of failure.

• Specs: 120V primary | 12/24V secondary | 40VA rating | Class 2 control transformer | Replaces legacy part numbers HT01BJ115, 19EA41612, and 19EA42612
• OEM vs Generic: This is a genuine Carrier OEM part. Factory-wound transformers meet exact VA and impedance specs for the U19X125U48A control board. Undersized or off-spec generic transformers can overheat, trip the fuse, and damage the control board — far costlier than the part itself.
• Install difficulty: 3/5 — Always disconnect power at the breaker and confirm 0V with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter, wire nuts or quick-disconnects. Photograph all low-voltage wiring before removal. Check for any shorted wire in the 24V circuit before energizing the new transformer or it will fail again.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before the cutoff.

Compatibility: Factory-matched replacement for Carrier model U19X125U48A. Always verify the transformer's VA rating and primary/secondary voltages against your unit's wiring diagram before ordering. Need help confirming fitment? Our HVAC parts specialists verify compatibility before you buy — no guesswork.