A/C not blowing cool air

Out of the blue, A/C is blowing hot air. The A/C compressor is engaged and turning. The A/C compressor discharge temperature is very hot (normal, I do not have a discharge gauge to measure the pressure). The A/C compressor suction side temperature is slightly above ambient temperature. Normally, the A/C compressor suction side temperature is cool to cold to touch when A/C blower is blowing cold air. For the pass three years I have had to add three to four ounces every two to four months. I added a full four ounce can of FJC stop leak, but that did not help.

Any suggestions would be greatly appreciated.
Thank you,
Ken