I have a Chevy Cavalier 2003 and there was a point in time I believe when my AC wasn't working at all. I eventually learned that all I needed to do was change a relay under the hood and it started working. When I say working I mean that the fans were turning again. Before that, I could feel cold air blowing out but only if I was driving fast on the highway.
Soon after that issue was fixed, I started to have an issue where I could not adjust how much air I wanted to blow out. Usually there is an option to have High, Med, Low air. The air would only blow out on the "High" setting and it is still that way today.
The issues continued after that. Now the problem is that the air will still blow out (only when the knob is turned to High) but unless I am driving fast, the air is hot. The fans are working still and air blows out, but it will be hot air unless I am driving fast or it is already somewhat cool outside. There is no smoke coming from my car or strange smells. I do not notice anything leaking from under the car either.
Even more recently my car has been overheating a lot too. I am not sure if this is related to the AC issue or not but the temperature gauge will go up really high when I am idle for so long. It HAS been really hot out but normally this wouldn't be an issue. I would have to start driving again for the temperature to go down. When the car overheats I can hear the car making this type of "pressure release" sound over and over like its releasing air or something and the car would kind of shake a little more but not much.
When it comes to the fluids, I check to see if something is in there but I am not sure of the quality of the fluids. With what I described, I am also not sure if poor fluids would cause this.