What is good Freon? Any Freon that does not contain Sealant or Stop Leak. If you look for Good Freon, you will notice that none of the cans have a hose attached. These are virgin cans of Freon and the only ones that should be used to charge an A/C System. The good Freon cans are also friendly to the machines that used by shops to recharge the A/C System. Call Automotive Blessings before adding any Freon to your car if you’re not sure if you have a good can or a bad can.