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Automotive Air Conditioners

Accumulator:

Orifice type systems use an accumulator that is connected directly to the evaporator outlet and stores excess liquid refrigerant. Since liquid refrigerant going into a compressor can do serious damage to the compressor, the main purpose of the accumulator is to isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers, also remove debris and moisture from a system. It is also a good idea to replace the accumulator each time the system is opened for repair or anytime moisture and/or debris is of concern.

The New Refrigerant - R134a:

The reason vehicle manufacturers choose R-134a to replace R-12 is because R134a comes closer to the cooling properties of R-12 than any other alternate refrigerant. Even R-134a is so close to R-12; it is not a direct replacement. They are chemically different and incompatible because each requires a different type of compressor oil and desiccant. Since they are different, federal law prohibits mixing the two to prevent cross contamination. It is also federal law that shops doing A/C work are required to recover and recycle R-12 whenever they perform any repairs to an R-12 system.

Even though they are different, R-134a can be used in an R-12 system provided the system is converted or "retrofitted" to the new refrigerant. The way this is done will vary from one vehicle to another, but in most cases it will require:

1. Removing and recovering all the old R-12 refrigerant from the system.
2. Changing the desiccant (accumulator or receiver/drier) to one that is compatible with R-134a.
3. Adding compressor oil that is compatible with R-134a (PAG or POE oil)
4. Installing R-134a fittings (which are different from the threaded fittings on R-12 systems.
5. Recharging with system to about 80 percent capacity with R-134a refrigerant.
6. Labeling the system to identify it has been converted to R-134a.

Factory R-134a systems are generally equipped with barrier style hoses to reduce seepage that can lead to refrigerant loss over time. It may not be necessary to replace the hoses when converting an R-12 system with non-barrier hoses to R-134a as long as the hoses are in good condition. This is because the hoses have absorbed oil that forms a barrier of its own. But if the old hoses are leaking, they should be replaced with new barrier style hoses.

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