The thing about winecooler a to remember is that the air it's putting out is cold air, but at one temp. The temp is controlled by how long the cooling unit runs, not by the temperature of the cold air being produced. So, whether you have the thing set to 55* or 65*, the cold air coming from the cooling unit is the same temp, it will just run longer to accomplish the lower temp.
So, the ETC works by turning the whole unit on and off based on the settings you input, and it has it's own temp sensor you'll wire when setting it up. When the etc turns the cooler on, the cooler will be set to the lowest setting... but the ETC will cut power when the temp it measures matches what you've input on the ETC. Even though the wine cooler may be set to 55*, if you have your etc set to 65*, it will cut power when the temp reaches 65*, the wine cooler doesn't have a chance to run until it hits the lowest temp setting.
Make sense?