Control Panel Reads Incorrect Temperature

[DrKev]

I inherited a nice little spa that has a nu-wave a24 control pack. It has run great, and since I only use it once or twice a week, I keep the temperature turned down by way of the control panel, and then turn it up a few hours before I need it. I went out last night to use it and was surprised to find that the control panel said it was at 101 degrees very quickly but when I felt the water, it was only luke warm. I'm guessing the thermostat has gone bad, but what do I know. I shut it down and when I restored power today it immediately read 90, which of course was wrong. Any ideas before I go replacing the thermostat to see if it fixes this? Thanks