Welcome to the forum. If the air compressor works or is easily repairable then its worth far more that way than as scrap. Mostly the weight comes from the steel in the tanks and steel is less than $0.10/lb. So I don't think you found a pile of money in the garage. More can be made by seperating the different metals. I suggest you read the sticky threads to begin and then work from there. There is a serious education available for free by just reading the old threads.

Also call the local scrap yards and ask about selling the compressor whole and what the price for steel is. Mike.