However, moisture mixed with refrigerant creates much more corrosion trouble. Refrigerant such as R-12, containing chlorine, will slowly hydrolyze with water and form hydrochloric acids. This acid greatly increases the corrosion of metals and could corrode copper plating. Heat increases the rate of corrosion due to acids because higher temperatures accelerate the acid-forming process. This acid attacks all the materials it contacts.
Refrigerant oil presents another problem caused by moisture.
In fact, refrigerant oil attracts moisture and will absorb it rapidly if left open to the atmosphere. Water-formed acid mixes with refrigerant oil, forming a closely bonded mixture of fine globules. Corrosion becomes troublesome from the operating standpoint when metallic surfaces are eaten away and a solid, detachable product is formed. Sludge can cause a variety of problems. It will plug fine strainers, expansion valves and capillary tubes.