pat, I see you also went on "Romans" site. There you said it happens on hot days also.
Here is a little more for you to digest.
Diagnosing A Restricted Feed Device
To diagnose the problem, it is easy as 1,2,3.
1. Shut the blower section off
2. Start the compressor
3. View the evaporator coil and be sure that there is a "full frost" pattern from the enterance of the evaporator to the exit.
If there is a restriction, part of the evaporator coil will be free of frost.