AC quit - what to do?

My AC quit yesterday, maybe its blowing a little cooler
air than outside, its hard to tell. Here is the situation:

Last summer I had it converted to 134. It seemed to work
fine all summer and through the winter. I've put maybe
8000 miles on the car since last year.

Yesterday, was the first time I really ran it more than
say 20 minutes at a time. The compressor seems
to come on when I turn on the switch. At least you
can hear the click and hear the engine pull. I checked
the main fuses under the hood and all the fuses in
the car, they seem ok. I pushed in the valve on
the AC hose and freon squirted in my face. Seems there
is something in there, don't know how much.

Should I put a can of freon in it? I do not want to do any
damage by overfilling or something. I don't have the money
to take it to the shop. I don't know what else to do.

Any advice, please.

I got a thing with a guage and you attach a can of
freon to it. I go to put a can of freon in and the guage
says it has plenty. So I did not put any in.
The symptom definately is: if you are sitting and not
moving for a little while it will become slightly cool.
As soon as you are driving, it becomes not cool at
all.

Any suggestions?

Thanks.

I know it's been awhile since this issue became know, but I just joined so figured I'd add my two cents just in case. I had an a/c issue with my 87 CRX DX, and it ended up being a burned diode in the control board behind the a/c controls. Mechanic pulled a used one from a wrecked car and all works fine ever since. Cost was about $150 total.