Someone asked this a while ago, you don't know how much is in the system. It's best to drain and refill it completely under a vacuum, this is equipment that a pro has. They do it all the time and it should be easy for a pro but difficult for a DIY due to the equipment involved.Why can;t I just use the cans of freon at autozone?
May I add that when you run the defroster cycle to clear windows you are also running the ac to remove moisture from the inside air. using this function regularly in winter time will be sufecient activity to keep seals lubed. Thanks Eric AKA cadman1940You should use the AC during the winter so that the o-rings don't get dried out and leak the freon. Using the AC for 5 minutes once a week will keep them moist. If you never use the AC they get dried out and leak a little. When you use the AC it causes it them to swell and it can fix a tiny leak. I think after the 4th gen cars they changed coolants and it was never as cold.