R-12 Systems

The Freon refrigerant used is also known as R-12. It is odorless and colorless both as a gas and a liquid. Since it boils (vaporizes) at - 21.7°F, it will usually be in a vapor state when being handled in a shop. But if a portion of the liquid coolant should come in contact with the hands of face, note that its temperature will momentarily be at least - 22°F.
Protective goggles should be worn when opening any refrigerant lines. If liquid coolant does come in contact with the eyes, bathe eyes quickly in cold water, than apply bland disinfectant to the eyes. See an eye doctor.
When checking a system for leaks with a torch type leak detector, do not breathe vapors coming from the flame. Do not discharge refrigerant in area of a live flame. A poisonous phosgene gas is produced when R-12 is burned. While the small amount of gas produced by a leak detector is not harmful unless inhaled directly at the flame, the quantity of refrigerant released into the air when a system is purged can be extremely dangerous if allowed to come in contact with an open flame. Thus, when purging a system, ensure the discharge hose is routed to Freon recovery system and that no open flames are present.
Never allow the temperature of the refrigerant to exceed 125°F. The resultant increase in temperature will cause a corresponding increase in pressure which may cause the safety plug to release or the drum to burst.
If it is necessary to heat a drum of refrigerant when charging a system, the drum should be placed in water that is no hotter than 125°F. Never use a blow torch or other open flame. If possible, a pressure release mechanism should be attached before the drum is heated.
When connecting and disconnecting service gauges on the A/C system, ensure that gauge hand valves are fully closed and that compressor service valves, if equipped, are in the back-seated position. Do not disconnect gauge hoses from service port adapters, if used, vehicle gauges are connected to the A/C system. To disconnect hoses, always remove adapter from service port. Do not disconnect hoses from gauge manifold while connected to A/C system, as refrigerant will be discharged rapidly.
After disconnecting gauge lines, check the valve areas to ensure service valves are correctly seated and Shraeder valves, if equipped, are not leaking.