Too much pressure on low side

My SUV doesn't want to take any Freon, one can jumps up the pressure to 70PSI, compressor, condenser, accumulator, expansion valve, orifice tube have all been replaced and system flushed. not sure if high/low pressure switches need to be replaced, or having another issue. when i flushed the lines I put A/C flush in one side and it came right out the other. so not suspecting a plug anywhere, and old expansion valve and orifice tube looked decent, no particles or shavings. just trying to figure it out before summer comes around.