Air conditioning compressor shut off, low refrigerant, fully charged.

The only way to know if a vehicle's air condition is properly charged is to use refrigerant gauges to determine the high side and low side pressure while the system is running. Without gauges, there are a few things you can check:

1. With ambient temperature over 85 degrees Fahrenheit, when you first start the engine for the day, the compressor should engage and stay engaged. If it cycles off and on for more than one minute, or if the compressor fails to engage at all, there is a likelihood that the refrigerant charge is low. (If ambient temperature is under 85 degrees Fahrenheit, a small amount of cycling is normal, but the compressor should remain engaged for a longer time than it is disengaged);
2. If the compressor is not engaging at all, momentarily place a wire jumper across the two pins of the refrigerant pressure switch connector with the engine running and the system on. The compressor should engage. If it does not, the system is not working properly. If it does, there is likely insufficient refrigerant in the system.

The port in the larger of the 2 AC lines from the compressor is the port you charge at.

Need to leak check the system,recover the refrigerant,
vacuum out all air & moisture, I would assume was put
in there by any number of people trying to add to it over
the years with no a/c experience & not using the proper
manifold gauge set. Then charge to the correct number
of onces

It sound like it has a low charge but if you know that it is fully charged you may have a bad low pressure switch . Also make sure that the condensor fan is working properly and the system is not building to much pressure.

check fuse and relays
take pressure reading if low system will shut down

Do you hear the air conditioning compressor switch on (with the engine running) when you turn on the air conditioning from inside the car. Get a friend to turn on and off the air conditioning while you listen with the hood open engine running you should hear a clicking sound on and off each time the a/c is cycled on and off or the a/c clutch is not locking up the compressor. This may be due to many things (bad clutch, bad compressor, no power to controls or compressor clutch) but it could be a sign of low charge the system has a low pressure switch which prevents the system from being energized if the system has low refrigerant charge. By protecting itself it prevent catastrophic failure of the compressor and ensuing damage to the rest of the a/c system if the system looses it charge. You will need to have the system checked out by someone experienced in air conditioning work who will attach pressure gauges to your car and see if the refrigerant pressures are OK. The system naturally looses some refrigerant over time but if the system constantly looses charge then it has a leak that must be investigated and repaired before just recharging the system

no gas/

Is the compressor engaging? If not he needs to find if a sensor issue if its fully charged or a low pressure or refrigerant condition. You can have pressure without refrigerant.

refrigerant is added at the low side charging port, this port is located in the low side AC line from the AC compressor, it is the larger of the two AC lines from the AC compressor, you add until the pressure is stable at around 28-32 PSI with AC on.

If the system is not fully charged the compressor will not run. Check to see it the system uses 134a refrigerant for the cooling system. You can buy them in Walmart or other parts stores and try to charge it yourself. It will tell you under the hood by the systems tag how much refrigerant it takes.