I'm hoping that someone out there can advise me. My hot tub was shutting on and off when I turned on the GFI. A message of HL was on the display. Then it changed to r59, and I don't know what that means and have never seen it before. Now the display is alternating between showing 0 and then r59, and the tub is not even coming on, just making a little noise as if it is trying to start but can't. Also, at one point, my husband had placed a piece of insulation blocking off the vent that is attached to the side. Does anyone out there know if that would have an effect on the hot tub - the HL reading, for instance. If we can't figure this out, I think we will just have to drain the tub and just wait for spring to deal with it. Thanks for listening.