Hints and tips 1. Have your a/c system checked once a year to ensure it is working correctly. 2.run your a/c at least once a month even during the winter to keep seals lubricated. This can help to prevent leaks. It is good at demisting your windows to. 3.If your a/c stops working it is good idea to check to see if any fuses have blown first. 4. Modern vehicles require that the a/c system is recharged with the correct amount of R134a refrigerant to work efficiently. Using DIY top up cannisters may not recharge your a/c with the correct amount of gas and will not be able to detect any leaks. Over charging the a/c system can cause damage. The only refrigerant recommended by all vehicle manufacturers is R134a. (New vehicles use new bio gas.) Some top up cannisters do not contain R134a refrigerant.