Very good drawing Roy. A lot of people are under the misconception that the A/C uses outside air. The drawing clearly shows that it recirculates the inside air.
A word of caution do not over tighten the bolts that compress the gasket. They should be snug but not too tight or you will soon be replacing the gasket.
If the coil ices over it is not uncommon for water to drip inside. As was said, just remove the filter and look inside. The ice is easy to spot. Then the question is what causes it to ice over. The most common is a dirty filter. The second is running on low speed on a high humidity day.