My window a/c unit doesn't blow cold anymore. It was working great then all of a sudden, poof. The fan still blows and you can hear the compressor kick on, but no cold air comes out. Is this a simple fix or for the cost of a new one am I just better off replacing it?

Usually the cost to repair is 50 to 60% of the new value if it can be repaired at all..

A high % of the time windows units get very dirty and need to be taken apart and given a very good cleaning and this will help a lot,, but you said ( It was working great then all of a sudden, poof. ) so the cleaning probably isn`t your case,, so HVAC1000 probably has the answer