Technician Safety Information

R-12 Systems
The freon refrigerant used in car air conditioning is known as R-12. It is colorless both as a gas and a liquid. Since it boils (vaporizes) at at - 21.7°F, it will usually be in a vapor form 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 will be momentarily at least 22° below zero.
Protective goggles should be worn when opening any refrigerant lines. If liquid coolant does touch the eyes bathe eyes quickly in cold water. Then apply a bland disinfectant oil to 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 an 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 the system is purged can be extremely dangerous if allowed to come in contact with an open flame.
Never allow temperature of refrigerant containers 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 necessary to heat a drum of refrigerant when charging s system, the drum should be placed in water that is no hotter than 125°F. Never use a blowtorch, or other open flame. If possible, a pressure release mechanism should be attached to the drum prior to heating.
Use care when disconnecting or connecting refrigerant lines, always use a back-up wrench and be careful not to over-tighten any connection. Over-tightening may result inline flare set distortion and a system leak.
When making pressure checks on system with intermediate valves, be sure valve is in the intermediate position. If turned in too far, the hose connection will be closed, a position used for isolating the compressor. When closing the gauge port, do not over-tighten the valve or damage to the seat will result.
After disconnecting gauge lines, check the valve areas to be sure service valves are correctly seated and Schrader valves, if used are not leaking.

R-134a Systems
R-134a air conditioning systems should not be pressure tested or leak tested with compressed air. Some mixture of air and R-134a have been shown to be combustible at elevated pressures and can result in fire or explosion causing injury or property damage. To identify which type of air conditioning system a particular vehicle has, visually inspect the system for identification tags located on major components.