I am having a very similar problem. I have noticed when I run my A/C that it will switch to heater while driving. I can hear what sounds like a door moving under the dash when it switches. If I turn of the A/C wait a few seconds and turn back on the A/C will work again.
I have been trying to determine when this happens and I think its when the RPM's drop but not always. I will be checking the check valve and looking for any cracks in any hoses.
Besides checking the hoses in the Engine compartment and the check valve are there any other recommendations. I read something about the blend doors having problems in the 95 - 02 dodges. Heater Treater has a replacement part they say fixes a lot of Heater / A/C issues. Any thoughts on that? Here is the link. http://www.heatertreater.net/magento...ram-95-02.html
Thanks in advance for any help.