R134a is sold without any certificate to anyone at most stores including wal-mart. If you don't know what you are doing though you can end up hurting yourself, so, it might be worth spending a few dollars and letting a pro recharge it for you - most shops will do it for under $100. You could probably do it yourself for about $30 including buying a hose to connect to your system. If yours is leaking you probably want to add at least one can which has oil too.

If your system still has any R134a in it at all you do not have to evacuate it so you don't need a pump. Does the compressor still run at all when you turn on the A/C? If so it probably still has some in it. A shop with a gauge can tell you quickly if the system is completely depleted or not. If it is completely gone then I would suggest you have them find the leak before recharging. Good luck.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz