Over time, the air conditioning gases in your car will escape from the AC system. This is because all car air conditioning systems leak over time: Car engines vibrate, pipe connections move, and the rubber rings expand and contract to allow leakage.
This leakage can get worse when the air-con is not used during the winter months, thus allowing the small O ring seals to dry out – resulting in a gradual deterioration in aircon performance.
If this continues, eventually the system will not be able to function at all. This is when you’ll notice warm air or even hot air blowing from the vents. Time for a car air con regas!