a/c blowing hot

There's several possibilities here. Refrigerant level is the first one as too much can have the same effect as too little at times. Engine temperature also plays a part so be sure that is in the normal range. Lastly is flow. Given no leaks and apparently there isn't, the compressor pumps refridgerant at regulated cycles and that is a possible issue. On this one I might suggest a qualified A/C technician test for high and low side pressures and go from there. Thank you, Dan