Hello. I have the same problem as this post. https://forums.xfinity.com/t5/X1/PX013ANM-Contstant-Fan-Noise/td-p/3334716
My TV box was upgraded when I added internet service to my account a week ago. Since then the loud fan in the main TV box, STB Version PX013AN_4...... , has been running, even when the unit is sleep.
I saw the post above and would like a newer unit with a quieter fan. I am not sure why these are still being given to customers with this known problem.
Thanks for your help.
How far away are you from your nearest Xfinity Store? Mine gave me a brand new box with a remote and power supply. I swapped mine out and followed the installation instructions; problem solved.