Acid burnout occurs when acids formed inside the refrigeration system attack and damage the compressor motor windings, causing electrical shorts and complete compressor failure. Moisture combined with refrigerant and oil creates acids at temperatures exceeding 350 degrees Fahrenheit inside the compressor discharge area. These acids corrode copper windings, insulation materials, and bearing surfaces, reducing motor efficiency and causing catastrophic electrical breakdown.
Formation and Detection
Acid formation begins with moisture contamination of just 100 to 500 parts per million entering the system through leaks or improper service procedures. Compressor surface temperatures reaching 350 to 400 degrees Fahrenheit during normal operation accelerate acid generation. Brown or black discoloration of compressor oil, acrid odors during operation, and complete winding failure indicate acid burnout progression.
System Recovery Procedure
Technicians perform acid tests using color-changing paper reaching orange at 25 ppm acid concentration. Recovery requires complete system evacuation and flushing with approved solvents such as mineral spirits or specialized refrigeration system cleaners. New filter-driers with acid absorbent materials must be installed and monitored through multiple service intervals.
Prevention Strategy
Eliminating moisture through proper evacuation to 500 microns and maintaining tight service connections prevents acid formation. Annual oil analysis and filter-drier replacement maintain system integrity and extend compressor life.