Hi everyone, i've searched and haven't found anything similar to my problem. I have a 97 f150 that blows hot when I put it on high. I just fixed the small vacuum hose that allows to blow through the panel but it still won't blow cold on high. If I have the a/c on low, turn it on it blows cold air just fine. But the when I put it on high I hear something close or switch and hot air comes out. Another problem I had with this(or before) is I had someone add refrigerant and it was working great on high. Gave my thanks reversed, switched to drive and BAM hot air again. Idk if it's more than one issue or not but any help is greatly appreciated

 

Check to see if the compressor is running when it goes hot. If not, check the low and high side pressures when it is running. Add refrigerant as needed.

 

Your temperature blend door is busted and is flopping back and forth. There's nothing wrong with the sealed air conditioning system.