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.

well if it worked fine for two days and then quit I would suspect your refrigerant is fine.
I am not certain, but I would suspect that it probably does need to be changed after a period of time... but rarely.
In your case I would wonder if the system is clogged up. Did the car sit for a long time, or was the A/C not used for a long time?
When the A/C is running to the A/C lines under the hood get cold? If not, then it isn't circulating... or maybe the compressor is not working correctly although it is engaging.

Change the orofice valve.