The capacitor tester (Figure 1-27) is used to test capacitors to determine their specific capacitance value and to find out if they are good, open, or shorted. For field service work,, most technicians usually test capacitors using the resistance (ohmmeter) function o f the VOM.
There are times, however, when it is necessary to determine the actual value o f capacitance in microfarads (MFD) for a particular capacitor or group of capacitors. This task cannot be done with most VOMs. The need to determine the actual capacitance value may occur because the value stamped on the capacitor is unreadable. It is also done when it is necessary to wire two or more capacitors in parallel or series to make a substitute capacitor for one that is not readily available. Also, if motor problems persist even though previous tests using a VOM showed the capacitor to be good, you should use the capacitor tester to verify the capacitor’s value.
A capacitor tester must be able to quickly and accurately check for leaky, open, or shorted capacitors. It should be capable o f measuring the capacitance of capacitors ranging from 0.01 MFD to 10,000 MFD.