When you find that your hot tub water temperature is no longer hot, it's time to check the hot tub heater to see if it is working properly. One heater element you'll need to check is the high limit switch. If you find that this switch has tripped, this is a sign that your heat pump may not be defective.
You'll find this high-level limit switch in your heater cabinet. With the front panel removed, look in the lower-left corner of the cabinet. Attached to the inside left surface you'll find a white switch with a red push button in its center. This is your high limit switch.