Hi Michael,
Welcome to the forum! There are a number of different temperature sensors such as thermistors, RTDs and thermocouples. Some sensors need excitation. You measure voltages with the ADS1015. The voltage is then converted to temperature. The formula is dependent on the sensor being used, and most sensors are not linear throughout the entire measurement range.
What kind of temperature sensor are you using? What is the range of temperatures you will be measuring?
Best regards,
Bob B