Ac compressor will not engage when ac is on. System seems to be full of gas. Quit without warning. This is on a 2003 Nissan Altima with 2.5L. Secondary fan does come on when AC is switched on.

Check A/C compressor relay. When you say it seems to be full of gas(freon) have you actually put a pressure gauge on the system? If the pressure is too low, the compressor will not engage. If the compressor relay is functioning, check for power at the compressor clutch. If it has power to it and it still is not engaging, the A/C clutch may need replacing. It is usually almost as economical to replace the complete compressor with clutch installed than to just purchase a clutch. Keep in mind if you replace the compressor you should also replace the receiver/dryer also referred to as the accumulator.