Think I have the same problem on my NSX, there is no cool air coming at all.
I had the tightness of the system tested and all was OK, they pumped vacuum and then filled with new gas (r134 -it´s a converted system). The compressor is working but there is a stop somewhere in the pipings, they told me that the Expansion Valve is a common problem-part on most car models.
Read about the time-wasting job with the dash and also have the same question:
Can you do replacement of the Expansion valve from the front dept without stripping the dash?
Here is the part:
http://www.ebay.com/itm/New-Expansi...Parts_Accessories&vxp=mtr&hash=item1e6bc22f23
If there is a blockage in the system who ever serviced it should have been able to tell by the system pressures. I have never heard of a bad expansion valve. Are you sure the compressor clutch is kicking in?