Fl1 error on Sundance Palermo spa. Tried to run without filter. Changed flow switch. The most encouragement came when trying to purge air bubbles with hose. The temp light would light for a brief moment and then go out again with same error. Continued to try thinking if we do this long enough it will finally clear. Again, the temp light would stay on sometimes for a long moment, but error would always return. Would appreciate any help!