You can buy a laser temp gun, and measure the temp yourself, you should be able to hear the cooling fan running.On my MP, the fan kicks on when the internal cooling fan core board temp gets to be 110 degrees. I always keep theTemp gun close, because you should never let It get above 125 degrees or you rick frying your FC ESC board.
Please, be careful, and not fly it until you figure out, what the issue is.