The Freeze Control unit is designed to monitor pressure in the airline.
On cold days with high humidity it is possible to get line blockage due to the moisture freezing within the line. When this occurs the Freeze Control unit will automatically release an alcohol agent into the line to thaw it.
The Freeze Control unit allows for aeration in the winter and also keeps excessive pressure from building up in the compressor, possibly causing damage to bearings, etc.
This is an optional add-on to our windmills, one that we suggest for northern latitudes.