I do have one of the newer types with the digital controls which appears to make the by-pass more difficult. Also, my AC unit is on the small size (5300Btu) and uses 490 watts which should be OK. I am not sure about the startup power surge and it's impact on the STC-1000.
As far as incoming cool air sensor, the electrical schematic I have for a different brand AC unit had 4 sensors which is why I mentioned which sensor.
Thanks again for all the helpful comments.