Problem with air conditioner

What is your question?

My air compressor runs, but it blows hot air. What might be wrong? I took it to 3 mechanics and they said the comessor was running, but its still blowing hot air. Do you have any idea about cost to repair this or what I might check to diagnose the problem. I leave tomorrow for a trip to sunny, hot, Florida and the thought of the hot drive has me concerned.