Why does my ac blow cold, then hot, then cold then hot?

Well imagine that **Woody II in Sioux Falls, SD:** The question below was posted by **Daleg in Crestview, FL** on September 20, 2016 Why does my ac blow cold air, warm air, cold air..... on 2001 Chevrolet Express 3500 The ac has very cold air idling. The compressor is engaged. I have cleaned the coil. When driving the ac air will blow cold, then not as cold, and back and forth but will keep the cab cool. When it gets above 90 degrees out side it will start blowing hot. If I turn the knob to full cold, max ac, and high fan speed, it will eventually blow cold air for several minutes. I've stopped and the compressor is engaged and the high side is hot and the low side is cold under the hood.o As long as it is left on max ac and high fan speed it stays cold, but it can get too cold. If I tun it to ac and lower the fan speed it will eventually turn hot again. Is the problem in the control, an actuator or vacuum? 2001 Chevrolet Express 3500 > **by Daleg in Crestview, FL on September 20, 2016**