I installed the controller, the system is running & cycling (continues to get colder & colder). When I press "Set" for the set point, nothing happens. Nothing happens when I press the "Up" button, but if I press the "Down" button I get a readout of "A0" & pushing any other button does nothing. I have tried holding buttons, holding multi buttons, yet get nothing. I have to unplug the frig to get it back to the current temp reading.