When the water inside them freezes and swells, the AC line has frozen. When the water in the lines is below 32 degrees Fahrenheit, this occurs. Water expands and pushes the surrounding ice out of the lines as it cools and loses density. The cooling water cannot exit the line if it is frozen.
The pressure inside the lines rises, causing the lines to rupture, as the surrounding water freezes and expands, pushing up against the frozen cooling water. This may seriously harm your air conditioning system and necessitate costly repairs or possibly the installation of a new HVAC system.
Alert Signs Take extra precautions to avoid frozen AC lines if your air conditioner is more than ten years old. Older units might be more prone to freezing, but newer units often have higher insulation and are better suited to cold weather.