In cold weather, moisture in the air brake system can freeze. Ice in the lines or valves can cause them to stop working. To help prevent this, the air brake system may include an alcohol evaporator. When the air compressor runs, the alcohol evaporator puts alcohol vapor into the air brake system to help prevent water in the lines or valves from freezing. (Alcohol has a lower freezing point than water.) Use only the type of alcohol that is recommended by the evaporator’s manufacturer (typically some form of methanol).