Acids can do irretrievable damages to an air conditioner unit. But how would acids get into A/c. Acids can form and build up as a result of chemical reactions between components, materials of construction, lubricating oils, or impurities. Acids also form due to high temperatures which happen due to improper operation and non-maintenance of the machine. The acid thus formed can trickle into the refrigerant.
Therefore checking the system for acids should be at the top of chart during professional maintenance of air conditioner unit. Acid can be easily be removed before the compressor fails.