A modular ice maker 's thermostat can be tested and replaced individually.
Test the thermostat for continuity using a multitester set to the ohms setting X1. Start by testing the thermostat when it is cold (10 degrees). Insert one probe into the hole labeled "T" and the other probe into the hole labeled "H". The meter should indicate zero resistance (continuity). After the ice maker has warmed up, repeat the test and this time the meter should indicate infiinity (no continuity).
If the thermostat does not pass both tests, it should be replaced.