To repair a car air conditioner, determine if the R-134a is leaking by adding special dye to the system. If the leak is large, use a gauge to check the pressure level at the low-side valve. Avoid using other tools, as it is illegal. Repair the leak if you find one.
Air conditioning might not be working because the compressor isn't turning. Turn the air conditioning on, open the hood of the car, and locate the air conditioning compressor, which looks like a pump with several hoses attached to it. Make sure that the center of the pulley on the compressor is turning. If it's not, replace the fuse, repair all the loose or broken wires connected to the compressor, and replace the air conditioning switch on the dashboard.
Check if there is enough coolant in the system, and add more if needed. This is also helpful if the air conditioning is cooling, but not as much as you want it to. Make sure not to add too much coolant, as it can have a bad influence on the air conditioner's performance. If there is no coolant left in the system, contact a professional instead of trying to fix the problem yourself.
When conducting air conditioning repairs, make sure that you know exactly what you are doing, as it may be dangerous to interfere with the system without having the proper knowledge.