Hi Gary,
It looks like your Image 716 spa with the Icon 15 control system by Balboa has a bad circuit board. If it is overheating and the topside digital display is showing the accurate water temp. and the pump is running only the 2 hours in the morning and 2 at night, I would have to say your Balboa circuit board needs to be replaced. The retro fit board
54446 will do the trick. Please let me know how this works for you. Thank you!
Product Link: http://www.actionsparepair.com/icon.html#54446