I know this is an old forum but I wanted to thank you for this suggestion, which fixed my tub's problem. I found the forum while Googling for answers as to why my Jacuzzi J-280 was climbing to 110+ degrees after a service tech came and troubleshot a different problem. The same tech came back three more times and couldn't figure it out before I decided to look into it myself. Sure enough, the tech had the red and black wires backwards.
Thanks again, and I think I'll be calling a different place the next time I need service. How could that have been overlooked?