88 Crown Vic Ac problem

My car gets cold when I 1st turn on the Ac, however after a few miles, it starts blowing out hot air, just like the heater in on.Some time it will do this when i first turn the car on. I had the freon checked and it is ok. The compresser works fine and all everthing under the hood that should be cold is. I think that a flap is opeing or closing somewhere and letting hot air in or will not let cool air in. Can someone help me, it very hot

I would check your controls, not sure how it is on 88's but my hot/cold selecter is cable driven, and it came off once on the control side and I had to put it back on

Thanks for your help, that was the problem the cable came off. I had to drop the glove box to fix it. Now I am cool

great!, always glad to help :)