During Compressor Replacement
A new compressor comes charged with 8 ounces of refrigeration oil. Before installing the compressor, Measure the amount of oil in the compressor being replaced, then measure the oil in the new compressor make sure that the amounts are equal, this will assure that a proper amount of oil is retained in the system.
During Component Replacement
When replacing the evaporator, add 3 ounces; for the condenser, add 1 ounce. If an accumulator is replaced, drain oil from accumulator through the pressure sensing switch fitting (Schrader valve removed). Measure the amount of oil removed, and add that amount plus 1 ounce to the new accumulator. No oil needs to be added to compensate for loss when valves or hoses are replaced.