Heartfelt thanks to everyone who took the time to respond here and in the other area where I posted my request. Per one of the tests that somebody recommended we checked with the AC off and both temperature controls on cold, and the driver side was blowing hot air while the passenger side was blowing ambient air. My husband tapped on the top of the cylanoidsi on the duo valve and then turned on the AC and got cold air on both sides. Then we ordered the valve repair kit that another member here sent us a link to. Thank you so much to everyone for helping us make this an easy straightforward process when nothing around here seems easy. PS: I have to admit that my husband had to tell me exactly what to write because this really is not my side of the brain and he is very mechanical and we both appreciate you very much.