'05 C230 A/C Blows Warm

[fmmb]

Driven the car off and on today and then this afternoon when I went to leave the mall I noticed the A/C wasn't blowing cold.

I also noticed (because it was raining and the windows began to fog) if I turn the airflow direction to the top for windshield nothing comes out.

I also tried the A/C on the AUTO mode and it still blows warm.

When I arrived home I placed an A/C guage (one from an Interdynamic R-134 coolent kit that I had - although had never used on this car) and it was reading in the red @ 100 psi.

Anyone have any thoughts on how to proceed or what to look for?