R-12 Systems

The Freon refrigerant used is also known as R-12. It is colorless and odorless 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 repair shop. If a portion of the liquid coolant should come in contact with the hands or face, note that momentarily, its temperature will be at least -22°F.

Protective goggles should be worn and fittings should be wrapped with a clean cloth when opening any refrigerant lines. If liquid coolant touches the skin, treat as if it were frost bitten or frozen. If liquid coolant touches the eyes, bathe the eyes quickly in cold water, then apply a bland disinfectant oil to the eyes.
Never rub the eyes. See an eye doctor.

When checking a system for leaks with a torch type leak detector, do not breathe the vapors coming from the flame. Do not discharge refrigerant in the area of a live flame. A poisonous phosgene gas is produced when R-12 is burned. While the small amount of this 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, be sure that the discharge hose is routed to a well ventilated place where no flame is present. Under these conditions the refrigerant will be quickly dissipated into the surrounding air.

Never allow the temperature of refrigerant drums 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 A/C system, ensure gauge hand valves are fully closed and that compressor service valves, if equipped, are in the back-seated (fully counterclockwise) position. Do not disconnect gauge hoses from service port adapters, if used, while gauges are connected to 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 rapidly discharged.

After disconnecting gauge lines, check the valve areas to be sure service valves are correctly seated and schrader valves, if used, are not leaking.