Heating and Air Conditioning: Description and Operation

SYSTEM R-12

DESCRIPTION
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. But if a portion of the liquid coolant should come in contact with the hands or face, note that its temperature momentarily will be at least -22° F.

WARNING: Protective goggles should be worn when opening any refrigerant lines. If liquid coolant does touch the eyes, bathe the eyes quickly in cold water, then apply a bland disinfectant oil to the eyes. See an eye doctor.

WARNING: 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 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 into contact with an open flame.


WARNING: Never allow the temperature of refrigerant drums to exceed 125° F. The excessive 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 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 an 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.