Oil acid test kits (Figure SP-5-2) require that an oil sample be taken from the system. The test is performed following the specific instructions supplied with the test kit. Typically, this involves mixing the oil sample with acid test solutions in containers supplied in the kit. Finally, the condition of the oil is determined by comparing the color of the liquid with the various colors shown on a comparison chart.
Use of an oil acid test kit is normally limited to testing systems with a serviceable semi-hermetic compressor, where the oil sample can easily be obtained at a drain plug or oil fill hole. For systems that use welded hermetic compressors, testing of the refrigerant with an acid/moisture test kit is the best method.
If repeated testing is desired on an operating system, an oil trap with a Schrader valve can be installed in the suction line. The small amount of oil that collects in the trap can be drained out for testing using the device shown in Figure SP-5-3. After the oil sample is taken, the sampler is removed and the Schrader valve is capped.
