My air conditioner smells like vinegar

Most times, it from mold that has built up on the evaporator. You can have it cleaned and the also the ductwork with spraying in special cleaners. But before you do that, when was the last time you replace the cabin air filter? They should be replaced every 10 to 15K miles. I bet it is old, moldy and dirty causing the smell. I'd start by replacing it and see if the smell goes away. A $10 part.