Its about a 6 or 7 year old Catalina with a Value system 2000 (#54094 ??) control pack, 4 button topside air type controls. I just replaced the heating element in the 2" stainless unit in the control box. After restarting the unit, it ran fine for 36 hrs. then showed a "Sn" on the topside controls panel that soon changed to "Oh". The spa temp is set @ 100F and was actually much lower when I discovered the problem. I cut the power to do a reset, and the problem repeated. This problem actually began prior to install of new heat element, but I was told by a tech at local spa dealer that this was the proper course of action. Now that I have spent some substantial $$, I need some better advice. Any suggestions appreciated......