a/c

So I have a 91 sierra Z71, my question is about the a/c. I bought a retro fit system for the truck, it had already been evacuated, so I started the conversion, I started the truck, the compressor kicked on and off like 5-6 times then it stopped! not sure why, but now my a/c light is blinking. anybody have an ideas? I am so frustrated with this truck I could push it off a cliff. HELP.. Thanks, Brian