A manifolded condenser came out in the late 1980's. It cannot be flushed like the dual parallel condenser. It has its inlet and outlet on the same tube but has seams that separate about every five tubes down. Some manufacturers will not pay warranty time on a system flush but they will pay for a filter.
Flushing must be done with a liquid so grit is carried out. Do not use a vapor (shop air). Using 15 pounds of R-11 refrigerant was the old way that systems were flushed, before the hole in the ozone layer was discovered. Today, mineral spirits are often used for flushing. Mineral spirits are chemically related to mineral oil so they do not present a problem with the refrigerant on R-12 systems. They should not be used on R-134A systems.