I replaced my a/c capacitor 2 years ago. I just replaced it again 2 months ago. It just went out again! What can cause this to happen?

Usually it is a cheap brand capacitor. Most of the capacitors are made in China and there in lies the problem. They build them cheap and fast and that is what the manufacturers are looking for. If you buy a good quality capacitor from GE they will usually be made in Mexico and they are better than the ones from china.

Now for the ultimate capacitor get one from AmRad Engineering they are made in the USA. How about that!

http://www.americanradionic.com/component/option,com_frontpage/Itemid,1/

Look around there site. There capacitors meet really strict standards especially the military grade. Yep they cost more but worth every penny. It is all I use on test equipment.