How to Properly Size a Run Capacitor for an Air Compressor

How to Properly Size a Run Capacitor for an Air Compressor
How to Properly Size a Run Capacitor for an Air Compressor

How to Properly Size a Run Capacitor for an Air Compressor

When the capacitor for an air compressor is broken or damaged, it can cause a lot of problems and stress. Especially if we’re talking about the compressor for an air conditioner that goes out in the middle of a hot and humid summer, it can be especially frustrating. The great thing is, however, that the compressor capacitor is actually not that difficult of a task to tackle on your own. It’s a rather simple fix.

However, it’s absolutely essential that you select the right size capacitor for your compressor. If you buy a capacitor that’s either too big or too small, you run the risk of capacitor burning out yet again and even spraying liquid on other parts of the compressor or machine, which could lead to further damage or deterioration.

To help you avoid making a potentially bigger mess of a rather simple fix, let’s take a look at how to properly size a run capacitor for an air compressor. There are three primary ways to do this, so let’s dig in.

Check your owner’s manual

Most compressors will have come with an owner’s manual, or at least a specifications sheet. Check if your compressor came with one or the other, and see if it shows the required capacitor size. If you don’t see it listed here, you can either check the manufacturer’s website or call them to verify the proper capacitor size.

Calculate the size yourself

To calculate the proper capacitor size yourself, start by multiplying the full load amps by 2,650. Then, divide this number by the overall voltage supply for your compressor. The full load amps and voltage supply numbers should be readily available in the compressor’s manual. Once you’ve done this simple math, the resulting number is the capacitor’s MicroFarad (or MFD), which indicates the size of the capacitor you need.

As you shop for a new capacitor, look for a capacitor that is within 10% higher or lower in size compared to the MFD you calculated. Although not always the most accurate way to measure the right size for your new capacitor, this calculation works fairly well and will get you at least within the acceptable size that is needed in order for your compressor to get back up and running again.


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