Hi Brodin,
I've not used these sensors but know a little about them. They are thermopiles (a number of thermocouples connected in series). Thus they generate a voltage that is dependent on the temperature difference between the front (heated by the I.R. radiation) and back (attached to the case). The energy is supplied by the item measured so no supply is needed. Try connecting the + and - outputs to a digital multimeter set to volts and see what you get out. You will need to amplify the signal ( try an istrumentation amplifer IC) before you connect it to an ADC. You also need to measure the temperature of the sensor as it only detects the difference between it and the object being measured.
The data sheet is not very helpful, try searching for application notes. It may be easier (but more expensive) to buy a complete module with a conditioned output.
Hope this helps,
Robert G8RPI.