Disclaimer: I'm not a AC mechanic so please keep this in mind. I'm just wanting understanding for future reference.

The AC was working fine last week untill while driving home from work In a VERY hard rain almost to my house the AC just stopped blowing cold. There was standing water(puddles 1-3" deep) that I drove through on my way down the highway (US1) about 1/2 mile from my house but nothing I thought was out of the norm for a Florida afternoon. I wondered if my belt was slipping or clutch got wet or something along those lines. (I could not tell if the compressor was on or not at this point due to the pounding rain). So I cracked the windows got it to the house and parked it. I took it to my "non-mercedes mechanic" for him to put the gauges on it. It was low but prob just 1/2 can. The compressor was running and the lines felt cold all the way into the cabin. This is where he was at a loss. (Yes it will be going to Pierre this week) I noticed on the way home it would not change temp at all with the climate controller set to hot or cold. As I said I'm not a mechanic so forgive my terminology, but wondered if there was something like a "blend door" that controlled the amount of cold/heat into the cabin of the car?
Thank you for any help/information you can lend here!!
Hip

__________________

2006 Jetta TDI DSG 320k miles
1997 Ford F150 325k miles 4.2L V6 "Work Truck"
2008 Tundra 225k miles 5.7L
1982 240D.....sold
1984 300D...Totaled OUCH!
1985 300D Turbo 222k miles "Dos" sold to 79Mercy
1986 300SDL 98K miles "The Beater"....sold
1987 190E 2.3 16v Euro spec 115K miles....sold