Your post led me to what was most likely the problem. The water pump was working intermittently....actually would come on, but shut off within a few seconds, then start again. I checked to see if it was working...and it was...initially, but never even considered it again, until you suggested the backwards thing. I traced the wiring, but found no problems with it. Only when I ran a different 12v power source to the pump, was I able to see that it was stopping / starting for no reason. Thanks for not trying to "re invent the wheel". This is the reason I use this forum....not to have some "genius" ask me questions like..."did I have the switch on?'....or "why did you let it get to 180 degrees?". Thanks again.