How many ohms should a capacitor have

How many ohms should a capacitor have

Capacitors are used not only in the air conditioning industry, but also in electronics and in many other areas where motors are needed, such as microwave ovens. The technology was invented in the Netherlands in 1746, and a famous application of it was Ben Franklin's experiments with kites in 1752.

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Capacitors are one of the most commonly replaced components in air conditioning systems. These capacitors store energy to give the motor the start it needs, known as a motor starting capacitor. Another type of capacitor that provides a little extra energy to keep the motor running efficiently is the electric motor capacitor. Both types of capacitors store energy and discharge it in the same way as a small discharge caused by static electricity on a dry winter day. Testing capacitors with an ohmmeter is relatively simple, but additional electrical safety is required to avoid electrocution from stored energy.

Signs of defective capacitors

Slow motor operation is an obvious sign that the motor is running on a defective capacitor. If the air conditioner blower motor does not run as it used to, or does not move at all, it could be a sign of a weak or defective capacitor. This is because the motor run capacitor is no longer supporting the motor and the motor no longer has enough "push" to run.

A quick way to check a capacitor is to unplug the unit, look around and locate the capacitor. Often, a defective capacitor will show signs of bulging or leaking. This is an obvious sign that the capacitor is defective and should be replaced. Do not operate the appliance until it has been replaced with a suitable capacitor.

Signs of a defective starting capacitor

Motor starting capacitors are not easy to diagnose unless you check for bulging or leaking capacitors. These capacitors also provide the "push" to start the motor, but are typically used for compressors in central air conditioning and air systems, and for any motor that requires a significant amount of extra power to start. The extra power is supplied to a specific set of motor coils to accelerate the motor, and these coils are usually disconnected when the motor reaches speed. If the motor has a faulty starting capacitor, the motor will overheat when attempting to start.

If you hear the compressor contactor make contact (a distinct "click" from the control box and wait for the external fan to start) and the pipes do not cool, you may have a faulty start capacitor or a faulty compressor. More advanced diagnostics can take a little longer than the average DIYer can safely handle. Some things are best left to the professionals.

Checking the capacitor with an ohmmeter.

Now that you have determined that there may be a problem with the capacitor, you need to confirm your diagnosis. The best way to do this is with a capacitor tester or multimeter that can measure capacitance. If you have a simple ohmmeter, you can test the capacitor; however, it will not tell you if it is weak. It will only tell you if it is capable of storing energy.

Turn the device off or disconnect it from the mains.

Set the ohmmeter to its highest value.

Discharge the capacitor by shorting the terminals with a capacitor discharge tool.

Remove the wire connections from the capacitor terminals.

Connect the test leads to the capacitor terminals.

Ohmmeter reading

It is important to observe the meter and understand the reading when the test leads are on the capacitor. The meter should immediately turn to zero ohms and then the resistance gradually increases. This is an indication of a good capacitor. If the resistance does not increase or decrease, the capacitor should be replaced. Remember to read the label on the capacitor and buy exactly the same capacitor. Don't settle for second best; bigger is not always better when it comes to capacitors.