The only thing original is the rear bags, which leak a little. .
There is your culprit.. the original rear bags, which leak.
NO doubt they have buttloads of water in them and in their lines.
it's a 200.00 fix, put two NEW rear bags on the car and make sure you atleast attempt to blow out the lines with compressed air that IS connected to a DRYER.
{no need in blowing more moisture into the system}
If the system is overwhelmed with moisture a battery of spider valves wont be able to solve it. it's take hundreds of cycles to evacuate all the moisture.
This got me to thinking, how do Mechanics evacuate moisture from Air Conditioning?
By putting a vacuum pump on and pulling the system down with vacuum.
Moisture will evaporate at a lower temperature when under a vacuum.
I'd be willing to bet that pulling a vacuum on a system with no leaks would go ALONG way in getting the additional moisture out of the system, so you dont contaminate the new parts with water.
"just a thought from the far side"