When it warms up the power goes off, and the power button flashes orange once every 5 sec. Indicates cooling fan not running. The fan seemed to be running slow, so I replaced it. Still does the same thing. Is there a temp. sensor that could be bad?

It's possible.

I can't help out much more without a model number.

Thank you. The model number is PT 50 LC 14

On that model there are three fans that need to be operating, otherwise you could get that flashing code. So check all three fans.

If it was the temperature sensor on that model, it would likely be a different error code.

I'm guessing the fan you looked at is the easiest one to see, which on this model is the one just outside the lamp housing. Since that one is working we can assume your power board is supplying voltage to your fans.

It is likely one of your other fans that is causing the shutdown. The problem is that servicing the other two fans is replacing the projection unit (optics block). Unfortunately this part is no longer available at most parts suppliers and even if it was the list price is over $500 USD.

It's possible to take the optics block apart and try to service it, but it's easy to cause problems when one takes apart an optics block. I would call Panasonic to see if they can do something for you. Otherwise you are probably better off purchasing a new TV.