Acid/moisture kits are one of the methods used to test refrigeration or air conditioning systems for the presence of moisture and/or corrosive acid. Acid/moisture testing is normally performed as a preventive maintenance check or in conjunction with servicing procedures such as system evacuation /dehydration, refrigerant recovery, or refrigerant recycling.
Acid/moisture testing is important because many troubles in the system can be caused by the presence of moisture. Moisture, as it circulates through the system along with the refrigerant and compressor oil, may freeze at the metering device, causing it to become clogged o r partly clogged. In conjunction with high temperatures like those encountered in the compressor and condensing units, moisture may cause the refrigerant to break down and form harmful acids, which can lead to compressor motor burnout. In a properly operating system, the compressor oil circulating through the system along with the refrigerant lubricates and cools the compressor. If this oil should become acidic, its ability to supply the needed lubrication and cooling is reduced, which can result in damage to the compressor.
Acid/moisture test kits can be self-contained, as shown in Figure 1-20. This device is attached to a system service port for about 10 minutes to obtain a sample of the refrigerant in the system. A disposable test tube located within the tester contains chemical crystals that change color in the presence of acid and moisture. The tube is removed from the tester after a 10-minute sample period and compared against a color chart to check the acid/moisture content of the sampled gas.
Refrigeration oil acid test kits and oil analysis test kits (Figure 1-21) can also be used to check the quality of refrigeration oil in a system with a semi-hermetic compressor. This method is not commonly used on residential equipment because it is difficult to remove oil from hermetic compressors. Use of these kits normally requires that a sample of the oil be extracted from the system, mixed with the chemicals in the kit, and the oil judged to be good or acidic based on the color of the oil-chemical mixture. Some refrigeration analysis kits require that the oil sample be returned to the kit manufacturer for complete oil analysis.