It's the beginning of the fall, it's time to check your coolant.
This is a good time to think about your engine's cooling system. Regular inspections of your cooling system are very important. Also, be sure to follow the vehicle manufacturer’s recommended coolant change intervals.
The protective anti-corrosive additives in the coolant break down and lose their effectiveness. But antifreeze has two other very important jobs as well: It is used to decrease the temperature at which the coolant freezes. It is also used to raise the temperature at which the coolant will begin to boil.
It is important that the proper ratio of water to coolant is always maintained. Unless specified otherwise by the vehicle manufacturer, the coolant in most vehicles should consist of a mixture of 50% water and 50% antifreeze before being added to the cooling system. This solution not only prevents freezing, but also preserves proper cooling.
Adding more antifreeze to the mix to increase its percentage in the mixture is not better. After the ratio exceeds more than about 65% antifreeze to 35% water, freeze protection can actually diminish and heat dissipation can decrease, since the water is the primary substance used for this purpose. Coolant itself actually has fairly poor heat transfer characteristics. Having too much antifreeze in the mixture can actually cause engine overheating.
When having your A/C system professionally serviced, insist on proper repair procedures and quality OEM parts.