I have been battling a weird issue for 2 years:
When I Use my spa I get an error at around 90 F if I have the header cover on. After many hours of playing over the years, I just left the cover off all last season.
This year, I asked my local servicer to fix it and he just replaced the Hi Limit Switch, despite me saying I've read that's rarely it. I still get the same error in the same scenario... but not with the cover off.
a. How do I resolve the invoice with the service? I go nothing but a $30 part and a $180 "heater call" fee. Do I just pay them and try and fix on my own or should the heater fee include any necessary revisits?
b. Given this only occurs with the cover off, can some brilliant person here narrow down my next steps of diagnosis? How does one get off the unitherm governor cap to test that?