With 360K Ohm i was cycling between 35-40*F
With 380K Ohm i was cycling between 36-41*F
Those tests were done with a potentiometer and a fluke meter to verify resistance. I have since settled with using a 400k Ohm resistor.
Lower Ohms will result in colder temps. Higher Ohms will result higher temps.
I would recommend starting out with 400k ohm. I would also strongly recommend you monitor AC parameters with Forscan (not required but makes it really easy to see when the compressor is cycling on/off).
Testing Ohm range should be between 320-420k Ohms. Every vehicle is different so you will have to test and determine the best resistance for yourself.