IML: 70 autotemp

I hope everyone had a nice holiday. My wife got me some insulated coveralls because I am bound to do some work on the beast this winter. Before I start my question, I would like to thank Frank Winnips for his advice about the leaky windshield. I think I read somewhere that heavy condensation on the inside of the windshield is also a sign of a bad seal.

Anyway....I have an autotemp 1 system that does not shut off when I push the off button! Boy does it get hooootttt!!!! You would think that would not be possible considering it is an AUTOtemp system. My refridgerant charge only lasted three months before it all leaked out. My FSM says that if the system does not shut off when the off button is pushed it could be: 1) Check valve #2 ;or 2)push button control is bad. I tested the Check valve and it is good, besides the fact that I replaced it 6 months ago. So that leaves me with option #2 but shouldn't the system detect all the heat and do something about it even though I have no refridgerant? Could a sensor be bad? But I don't think refridgerants and sensors have anything to do with the inability to turn off. I have also tested the petentiometer dial and it is good, and I have replaced the water valve and water valve thermostat. Please help. You would think that a heater that does not shut off in the winter would be a good thing.