A/C Problems

I have a 97 Civic. The a/c was not cooling so I added a can of 134. The low side was reading 30 and the high side read about 230. After about a minute the low side dropped to just below 0 and the high to 200. I can turn the car off and wait awhile and the car will cool fine for a few minutes then it just blows warm air. Can anyone point me in the right direction of what to do?

Thanks
Scott

Are you sure your gage is properly connected?
I don't see how you could ever get the low side to "0"

Does your compressor cycle on and off while the motor is running?
If so, you're probably still under charged, and make
sure your fan motor runs when the AC is on.
If it doesn't, it won't cool when the car is sitting still.

Thanks for the response. I found out that the outside of my evaporater core was stopped up with insulation from the box that it is enclosed in. This was causing the system to freeze up and explains why the low side was reading zero because it wasn`t getting any circulation.