BobH

I have a Balboa Spa Control System that's been converted to 120 v; running a single 1-speed pump and blower. System works fine, circulating and heating for about a week or so, then it blows the 20 amp/250 v fuse at the F-7 location. I replace the fuse and all systems work fine for another week or so, then the fuse blows and system shows dr code. Repeat with new fuse and it works for a week then blows again. Any ideas or suggestions as to how to stop this cycle?