My whirlpool French door style refrigerator stopped cooling recently.

I have tried the following troubleshooting measures:

Unplugged the unit to let it completely defrost.
Cleaned the condenser coils.
Opened the back panel and verified the compressor is running.

I then got carried away and took the evaporator cover panel off inside the freezer section.

The circulation fan is running.
The line going into the evaporator coil is frosted, but the rest of the coil isn't even cool. Almost like it's clogged or something. I banged on it a little to try to restore proper flow, but that didn't seem to help.

See pic. http://m.imgur.com/dacrlsk.jpg

Any ideas? It's next to impossible for me to be available for a service appointment, as I do similar service work so I'm never home during service times.

Thanks in advance!