Ed, that is correct, in most cases when the purge valve needs kit is because of the cycling so often,
oil/water will not seat purge valve. this is where motorhome cannot build air pressure after stopping
for lunch, takes about 5 minutes to put o-ring on purge valve assembly. Location different parts of country where it is very humid the filter will not last as long in area like AZ. etc. Note: cycling of Purge valve
on air dryer. When the air pressure becomes greater than that of the preset cut-out, the governor
controls the unloader valve mechanism of the compressor, stops the compressor from building air, and
causes the air dryer to purge. As the service reservior air pressure drops to the cut-in setting of the
governor, the governor returns the compressor back to building air and cycles the air dryer back to
air drying mode. As the atmospheric air is compressed, all water vapor originally in air is carried along
into the air system ( as well as small amount of the compressor lubricating oil ) as vapor.
Dave