A/C not working

Climate control knob not responding.2000 dodge stratus, 86,000 miles, 2.4L

It may just be the way it is, I have a dodge dakota and when it runs for awhile hot air from the engine blows in through the vents slowy, I think its just the climate control valve is maybe messed up. But I have that problem too, but its nto a bad thing.

In the last 4 months my AC has stopped working twice.
I live in Austin, TX were it can become very hot and both time the AC has gone out was after being out in the sun for a long bit of time. It works just fine the rest of the time.
I keep my car in a garage so it is kept in the shade and most work days my car is in the shade in the late afternoon for a few hours before I drive home.

That seems to be the difference, when the car is kept somewhat cool and shaded, no issue with the AC, when the car get's heated up by the sun, the AC stops working.

I went to a shop and they said that my compressor was going, but that does not sound right to me. If the compressor was going, wouldn't it just stop working all together?

I'm sorry, I'm not sure I know the answers.

Gague reading? Do you mean the dash board temp reading? It seemed to rise a bit, but not over heat.

I have no idea if the compressor stops, I hear nothing usual and the vents keep blowing, it's just warm air.

The shop didn't tell me a thing but the compressor was going and needed to be replaced.

My father (who was with me the first time this happened) thinks it's low on freon and when the car heats up it freezes up.

To get the heater warm you have to be driving in an interstate setting for a little while to get any heat if it is very cold. It used to get hot just setting at idle. The a/c is the same way if it gets a little hot. If it is just a little warm then it gets very cold pretty qucik.
Any ideas

I have replaced the thermostat three times. The Air conditioner does the same thing. I turn the hot and cold adjuster and you can hear it change. I change the fresh air to recirculating knob and you can hear it change. The car still doesnt warm up and the air doesnt cool? I have also flushed the heater core.