If your car’s AC system is not working, there are a few things you can do to try and fix the problem. First, check to see if the AC compressor is turning on. If it isn’t, you’ll need to replace the compressor. Next, check to see if the AC lines are plugged in properly. If they aren’t, you’ll need to plug them in and test the system. Finally, make sure that all of the windows are closed and that the car is turned off before trying to fix anything else. ..