I had a guy come to me the other day, had the same problem. We put the gauges on, and it was reading close to what the required pressures were. When we took off the empty can of gas I had on the gage set all kinds of green stop leak came pouring out. I took it to the guy at the local station that had a gas filter and recharger tank. we let all the gas out of the high side. Some one had filled the thing with a ton of stop leak and oil. The stuff coming out was a nice color of green and foaming brown oil. After running a couple of small cans through the system and cleaning out the oil and stop leak, Viola it started to cool. NO GAS NO COOL, oil and stop leak do not make good cooling lol.
On the down side now the compressor is making some neet cliking noise as it isnt pumping mostly oil annd is pumping gas. the guy is going to have to get a new compressser and have to have the system cleaned to get whatever else is in the system out of it. It is cooling for now. but the shrader valves have a slow leak in it even after they were replaced. Not sure how long it will work but its 100 here in FL and the poor guy works for a theme park and has little money, it will get ran until it breaks