The refridgerant probably all leaked out. Have your system inspected by your local qualified mechanic that works on Air conditioners.
Do not try doing it yourself I had to fix a guys car because he kept adding cans of refrigerant with stop leak in it and he blew out every seal on the high side. The stop leak plugged the high pressure switch so it saw a pressure reading of 0 and kept running.
The compressor kept running.
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