How do I make the fridge do self diagnostic?

Regards!
The problem with the refrigerator is that the evaporator fan motor is not working because it does not reach 120 volts. When you check with the voltmeter the voltage that reaches you is around 22 volts. I Check the electrical diagram that is located on the bottom of the refrigerator and the 120 volts leaves the Beta Control terminal J1-6 and also indicates on a “Beta Codes” that has the refrigerator by
example, the first one indicates “2” Flashing- Open Thermistor. Ok, what I want to know is how to provoke the exercise so that the refrigerator makes the self-diagnostic. I already checked the 2 sensors and they gave me around 8 and 9 ohms and I gave them heat with a blower and both sensors changed from ohms to 3 y 4 ohms.