So I have this Fafaco solar heat controller that turns on and stays on when the switch is in the "on/test" position. I then set the temperature that I want , place the switch in the "auto" position. I can hear and see the valve/motor open up, and then it shuts off, and then it opens, and then it shuts off. sometimes it only starts to open and then closes. I can hear the relay click when it opens and closes.
I am prety sure its either a temperature sensor or a relay. the question is if it is the temperature sensor is it the one by the solar panels or is it the one by the plumbing? or is it a flakey relay.