I chatted with rep. from justanswer about my problem ref/freezer and found out about the defrost thermostat not working. My compressor is humming and warm and there is frost on the lower back wall of my freezer. My computer decided to shut down and reconfigure and i was not able to access the rep. any more. So, I am wanting to know where the thermostat is and how to diagnose if it is the problem or not. Please advise. I am just learning about computers and do not know a lot yet. Thanks, Virgil