How long does ac gas works? When should I refill gas in my ac ? How ac gas leaks?

The gas used for an air conditioner never runs out. An ac unit can be used for 5 years without needing gas refill if you use it wisely. But , If the climate or enviromental condition of your area is rusting or your location is near to sea or lake. Then the climate air would be rusting and it effects on the copper tubes of air conditioner which causes leakage in copper tubes and gas leaks.