Removed and replaced contactor, potentiometer and temp board. Incorrect probe. Used old probe to test. Unit not cycling correctly. New temp board bad. Will reorder and return. Left unit unplugged. 4-10-17 Tested and found unit's contactor chatters and stays engaged sometimes. Tested and found diode bad on board from com feed to relay to N/O contact, left two as you look down at board. Removed one side of diode. Unit is working. will obtain another so interface does not disturb the operation. Note: per Brian @ Garland, diode no longer needed, build into board. A bad will cause contactor chattering and sticking.