Cat 246c air conditioning problem

Does anyone know what the correct charge amount should be for a cat 246c? I have an intermittent cooling problem and the high and low pressure appear to be fine. The low was about 35 and the high at 225 at 90 degrees ambient temperature. I am considering replacing the accumulator and replacing the r139a since it may be a moisture problem but can't find out the ac specifications for the machine.

Cat 246c air conditioning problem