A/C System

GENERAL PRECAUTIONS
The Freon refrigerant used is also known as R-12 or F-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. 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° below zero.
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.
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 or F-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. Thus, when purging a system, be sure that the discharge hose is routed to a well ventilated area 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 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 that 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.




CLEANLINESS
Air conditioning systems are extremely sensitive to moisture and dirt. The importance of clean working conditions is extremely important, as the smallest particle of foreign matter in an air conditioning system will contaminate the refrigerant, causing rust, ice or damage to the compressor. For this reason, all replacement parts are sold in vacuum sealed containers and should not be opened until they are to be installed in the system. If, for any reason, a part has been removed from its container for any length of time, the part must be completely flushed using only R-12 or F-12 to remove any dust or moisture that may have accumulated during storage. In cases of collision repairs where the system has been open for any length of time, the entire system must be purged completely and a new receiver-dehydrator must be installed because the element of existing unit will have become saturated and unable to remove any moisture from the system once the system is recharged.
When making gauge connections, purge the gauge lines first by cracking the charging valve and allowing a small amount of refrigerant to flow through the lines, then connect the lines immediately.
Cleanliness is especially important when servicing compressors because of the very close tolerances used in these units. Consequently, repairs to the compressor itself should not be attempted unless all proper tools are at hand and a virtually spotless work area is provided.