Can I install my cable box inside unused fireplace?

We have installed our tv above the fireplace. Running cables to the fireplace using the fireplace's blower fan outlet to power tv and cable box. We have it completely installed and can see no cords, woohoo! We have not compromised the fireplace in case we wish to use it in the future (which I doubt in FL) but my problem now is, the remote is not making the cable box respond, then all of a sudden in runs the through the channels very quickly randomly stopping later. I left extra length of cords to move it around the fireplace and when I pull it completely out it seems to work fine, but not inside the fireplace. What is causing this and is there a fix?