A/C Blows Cold at Higher RPM but not cold at idle

So , I have an 06 Sienna Limited. The AC blows cold at speed. If the RPM’s are over 2000-2500 and higher the cold air flows. if I am at idle (stopped at a light, parked with engine running 1500 RPM or less) the AC blows less than cold (humid/non AC) air. Took it to a trusted mechanic he has since replaced the belt, Compressor w/clutch, and evacuated and put in all new fluid today. It is still doing the same thing. Any ideas??? He said it might be the expansion valve which necessitates taking the entire dashboard off.

Thanks fibber2, I will pull out the glove box today and see if the valve is reachable.

You probably have a problem with the electronics. I had a similar situation, and the cause of the problem was the sensor, which was contaminated. The fan wouldn’t turn on, and the air conditioner wouldn’t cool the car. You should also show your car to a good mechanic who will make a complete diagnosis. Nowadays, almost everybody does air conditioning repair, but there are very few excellent companies. It would help if you searched for a long time on the Internet to find a service that will inexpensively and qualitatively repair your air conditioner.