Heater problems

Should start this with weather facts we had two days of severe lighting in the area

The temp in my tub went way over 115 shut down pump and changed the temp control unit also changed the pressure switch because the temp control did not fix the problem as well I found at that time the GFI breaker did not work . Had a timer on the unit that I never used so took it out as well. Have the water at the correct level and have replaced the filters with brand new ones. When I reinstall the spa pac everything worked the heater came on the pump runs both slow and high speed after about a hour the light goes out and I cannot get the heat any higher then 75.If I turn the control down then back up the heater will not come on.Have adjusted the pressure switch so it is on the low side but did not help . When I had changed the pressure switch I could blow into it and you can hear the click in the switch as well in I think it is the relay now that does not click even if I hold the relay down it does not turn on the heater.

If you could help that would be great

[Mary]

You should take a voltage reading when you have the thermostat turned up to put the spa in a heat call. The light may have a shut off after an hour, a lot of spas will do this. You said the heater came on at first, how high did the temperature get?