Ac wont start help!!!

My ac just randomly went out, the only time i can get any air to blow is if its on high and then it still takes about 5-10 seconds to blow. When it turns on there is cold air for about 2 seconds then just warm air. The compressor kicks on for about 2-3 seconds and then cuts off and when it cuts off the fan for the inside of the car then turns on. Please someone help me fix this because im trying to sell car pretty soon. Im really hoping compressor is not going out.

I know very little about AC system, but to me it sounds like the system is low on refrigerant.

Good luck,
Sam