I doubt this is normal. When I'm in the attic the cold pipe just above
the drip pan really blows a lot of cold air out at me. I've called a
repairman but he can't get here for a couple of days. Anyway, I'm
wondering - assuming this cold air shouldn't be leaking out like this -
would it maybe just involve refitting the pipe/valve or could it be
something worse?

We called for a repairman last week because our unit was just not
cooling our house but then tonight we found our carpet was wet behind
the wall where the AC unit sits in the attic. When I went to see what
was going on I saw that the pan was full of water but was not flowing
out of the emergency drain but once I cleared that drain the pan
emptied fine. I know having water in the pan is normal and that it is
supposed to evaperate before it overflows but I haven't run across any
thing that might help me figure out why it's not evaperating. The low
(normal) condensation drain is working fine. Could it be the leaking
of cold air is hampering the evaperation? Any thoughts, ideas or
suggestions would be greatly appreciate.

TIA.

JB