There is no charge in my system, it leaked out. I don't have a vaccuum pump, how can I remove the air, could I run some r-22 through the system to chase the air? If so how can I do this. Do the scharder valve o-rings go bad? If so where can I buy them

First, you need to find and repair the leak. Next, you have to vacum the system down, what you are probably talking about is purgeing the system and it is illegal to do this,and you could face big fines, my advice is to call in a pro, this may be a simple fix, but if you don't get the air/moisture out of the system you will damage it and may need to replace it.