Just as an fyi, it's not always a low charge that causes that fast cycling. I seem to remember when I had a new compressor installed on my 84 Z28, the A/C tech got the system charged properly, but it was still cycling too fast, so he adjusted a screw on the dryer pressure connector to slow the cycling to normal intervals. If you disconnect the plug on the dryer, and look into the center of the pressure connector, you'll see a slotted adjustment screw. I should think most competent A/C techs would know about this adjustment. I'm not, and I don't but watched him fiddle with it until things were correct.
