Why is it necessary to evacuate the system before adding freon?

Evacuating the system before adding freon is essential primarily to remove contaminants and moisture that may have accumulated within the refrigeration system. When moisture is present in the system, it can mix with the refrigerant and lead to the formation of acids, causing corrosion and damage to components like the compressor and evaporator. Contaminants, such as dust or dirt, can also impair the overall efficiency and functionality of the cooling system.

By performing a proper evacuation, these harmful substances are eliminated, ensuring that the system is clean and free of moisture before introducing new refrigerant. This process helps maintain the integrity of the system and ensures optimal performance once the freon is added. Proper evacuation is vital to prevent problems that could arise from the presence of contaminants and moisture, ultimately contributing to a longer lifespan of the cabin atmosphere control system.