Checking the acidity and/or moisture content of refrigerant oil is one of the methods used to test if a refrigeration system is clean and uncontaminated. But how can you take an oil sample without an oil plug?
Today more and more systems are incorporating microprocessor controllers into their design. Troubleshooting the operation of these controllers can be a little tricky at times, but if broken down into sections it can be easier to handle.
I have always been impressed with the true refrigeration professional; the type of guy that not only is able to fix a problem, but also understands the why behind the problem. These guys are not satisfied with just knowing how to replace a failed component . They want to know why it failed.
One type of starting relay used on fractional-horsepower compressors is the current relay. A defective current relay can cause a compressor not to start. One popular method of troubleshooting this type of starting relay is with an ohmmeter.