Technician Handbook Air Conditioning for Collision Repair Refrigerant Line Using a thermometer, check accessible refrigerant lines to confirm system operation: Temperature • Low-pressure lines should be cold. In humid weather, moisture may condense on these lines. • High-pressure lines should be hot. - A high-pressure line that feels cold indicates a pressure drop due to an obstruction in the system such as a clogged fitting or a crushed refrigerant line. 26 Collision Repair & Refinish Training