It is either a bad ground or a bad shield on a cable.
Can be any cable the tv had connected to it. Or anywhere along that signal path.
I've seen this on antenna amplifiers, stereos, tvs and production equipment when we were filming. Usually due to a non pro piece of gear someone had brought into play. Good luck.
BTW, adding the heater motor to the mix is interesting. Not usual. Look at the 12 volt line running the heater blower.
Try pulling fuses on the 12 volt side then on the 110 side breakers.
Good luck... This stuff is a bear to find. Just don't shotgun it. One thing at a time. Write down what you've done to keep you honest!
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