We own a gulf coast spa rotundra (we got used so unsure of the date of tub but we think 2003, no manual came with it) that stop putting heat out a week ago. We had it up to 103 for one weekend, turned it down during the week, went back out to turn it up and not heat. We replaced the heater element, the flow switch and still no heat. We cannot find a hi limit switch any where on the tub. We just got in the temperature probe and when we install it, it states the temperature is 124 and shuts the whole tub down (water temperature is actually around 45 degrees) if we unhook the probe it states the water temeperature is 32 on the top side of the tub and no heat. Everything else works on the tub both motors, jets light etc. Just cannot get any heat. no error codes on the top side of the tub. The heater light does show that it is on when we crank up the numbers but no heat. Any suggestions?