Dash AC blows cold,then warm,then cold when switched to max

[Woody O 5]

On this trip to FL, dash AC blows cold air, then became warm air, turned AC to Max, blew cold air for maybe 30min., then began to blow warm air, switched back to regular AC, starts to blow cold again for 30min. or so. As long as I continue to switch back and forth, I have cold air.  What is defective?

Edited March 16 by Woody O
For a better explanation

[Jonbrooks 10]

Probably need to have service tech throw gauges on it and read the pressures to start diagnosis. 

[pennzo 7]

Along this same thread, (sorry, don't mean to hijack, but felt my scenario is similar) if my Dash A/C has never worked since we've owned the Coach (well, when we bought it in 12/2015, it kinda worked, but it could've been just cooler air coming in from outside 🤭) and I can't get a service appointment down here in Tampa for months, does anyone have suggestions?  Is this a DIY option or better served setting an appointment and waiting?  😣

[Ivan K 93]

43 minutes ago, pennzo said:

Along this same thread, (sorry, don't mean to hijack, but felt my scenario is similar) if my Dash A/C has never worked since we've owned the Coach (well, when we bought it in 12/2015, it kinda worked, but it could've been just cooler air coming in from outside 🤭) and I can't get a service appointment down here in Tampa for months, does anyone have suggestions?  Is this a DIY option or better served setting an appointment and waiting?  😣

First thing would be to see if the compressor is even turning when you turn AC on and go from there.

[powersltc 0]

I would try changing out the resistor.   Inexpensive.   Controls heat and air conditioning. I couldn't get heat, changed the resistor and got heat.  Haven't try A/C yet  but I think I need freon.