Ford Repair: Ford Sable 1994 Air Conditioner Intermittent Cooling, ford dealer, freon

Question
My 1994 Sable A/C will blows cold air (46'F on a 90'F day) then after 15-to-45 minutes it will start blowing ambient air and this ambient air can also last for 15-to-45 minutes.  This happens in park mode or when driving.  The A/C never blows cold air for more than 45-minutes and usually only 15-minutes.  The Ford dealer checked the A/C and said the compressor and Freon level are good.  They didn't know what else to try.  

Answer
Hello and thanks for the question...I'll try to help.
Unless they completely evacuated the system...they can't tell if the system is properly filled or over filled.
I would suggest to you that you take your vehicle to an AC shop and have them remove ALL of the freon and recharge it with the proper amount.
Erik