Air Conditioning Refrigerant Precautions
R-12 SYSTEMR-12 refrigerant is colorless both as a gas and as a liquid. Since it boils (vaporizes) at -21.7°F, it will usually be in a vapor form when being handled in a repair shop. However, 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 come into contact with eyes, rinse them out quickly in cold water, apply a bland disinfectant oil and see a physician as soon as possible.
When checking a system for leaks with a torch type leak detector, do not breathe the vapors coming from the flame. A poisonous phosgene gas is produced when R-12 is burned. The small amount of gas produced by a leak detector is not harmful unless inhaled directly at the 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 is necessary to heat a drum of refrigerant when charging 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 overtighten any connection. Overtightening may result in line flare set distortion and a system leak.
When making pressure checks on systems with intermediate valves, be sure valve is in the intermediate position. If turned in too far, the hose connection will be closed, which is a position used for isolating the compressor. When closing the gauge port, do not overtighten 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 SYSTEM
R-134a refrigerant is a non toxic, non-flammable, clear, colorless and odorless liquefied gas.
R-134a is not compatible with R-12. Even small amounts of R-12 in a R-134a system will cause lubricant contamination, compressor failure or improper system performance. Never add R-12 to a R-134a system.
R-134a air conditioning systems should not be pressure tested or leak tested with compressed air. The mixture of air and R-134a has 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.
Avoid breathing R-134a refrigerant and lubricant vapor or mist. Exposure may irritate eyes, nose and throat. Use only approved service equipment to discharge R-134a systems.
On R-134a systems if a halide leak detector is used to check the system, refrigerant coming in contact with halide detector flame may produce phosgene, a toxic gas.