Two possibilities:
1. Either a rock knocked off your AC Condenser, in this case it is bad new. Read through this thread:
http://www.odyclub.com/forums/showthread.php?s=&threadid=40871
or...........
2. This was my case....Not sure this would help but I think it may well be bad AC Clutch and Stator.
In early August 2010, while on vacation in Hilton Head SC, my 2007 Ody just developed bad AC clutch at 37 months and 34K miles, after some negotiation with Honda USA, they split the cost of repair:
I paid 50% of the $600 bill = $300.
Not happy but better than $600.
I have owned many cars, the AC Clutch usually fails after 150K miles, not at 34K miles!
In my case, they had to remove the compressor, so the need to evacuate and then recharge with R134a.
From my reading of your post, this job by itself (replacing the AC clutch) does not require evacuating R134a but the space is tight in a FWD transverse engine, so they often remove the compressor to make it easier.
Anyway, next time if the AC clutch goes out, I will DIY: simply loosen the compressor mounting bolts and angle it down a bit to replace the AC Clutch, this way I do not have to evacuate R134a.
These are the parts Honda replaced on my 2007 LX:
38900-RGM-A01...CLUTCH SET....$130 online
38924-RGL-A01...STATOR SET....$58 online
Normally you don't need to evacuate R134a to install these parts because they are basically mechanical parts on the pulley. However, the space on the Ody is very tight and the compressor should be removed (serpentine belt needs to be removed etc.). In the process of removal, the R134a needs to be evacuated and when done, recharged with R134a.
If your mechanic can find a way to install these parts without removing the compressor, it would save a lot of money.
First thing first, go buy a AC kit ($15) at local autoparts store and measure your AC pressure, if the pressure reads nothing, see #1 above. Here is info on the AC recharge kit:
http://www.idqusa.com/proddetail.php?prod=GBM-2CS
Let us know the outcome!