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This OEM control transformer is the factory-specified replacement for the Carrier GB1AAV048111AGJA packaged gas/electric unit. The transformer steps down 120V line voltage to 24V to power the low-voltage control circuit — including the thermostat, contactor coil, gas valve, and all safety switches. When this component fails, the entire control circuit goes dead: the thermostat goes blank, the system won't respond to any call for heating or cooling, and no error codes will display on the control board because there is no power to generate them.
Compatibility: Designed for the Carrier GB1AAV048111AGJA packaged gas/electric unit. Cross-reference OEM part number HT01CN001 against your unit's data plate and wiring diagram to confirm fitment. The GB1AAV048 series designates a 4-ton packaged unit — confirm your VA rating and terminal configuration before ordering. Have questions about fitment? Our HVAC parts specialists verify compatibility before your order ships.