Strange A/C Problem

[tomj22]

1993 Toyota Tercel - Compressor kisks in and stays kicked in with AC button pushed and fan on. Blowing warm air. Slide control from cold to hot working fine. I can hear the door open and close and when I slide it to warm it blows very warm. When I slide it back to cold it is cooler but still warm. The freon is up to par - I checked it and the low side pressure is about 40 (in the blue). I do not know what the high side pressure is. All lines stay equally warm - not cold and none hot. If I release freon by from the valve it is warm. I know when I put freon into a system (not this car) it is freezing cold. Dumb question here but is there such a thing as freon loosing it's ability to cool? Just to re-cap. Compressor does kick in and stay on. Slide switch working from cold to hot. Fan works fine. Any thoughts? This is my daughters car she just bought a week ago. The AC was fine for 2 days and now this. All the above checks were made today.