Should I involve my son to communicate with my ex husband?

My ex scheduled a road trip that includes a stop at my son's place. I asked him to stop here to pick up some things that I am unable to take to my son myself. He said he would do it. I asked him to give me an idea when he was going to be by me. He has not told me when he will be here. Should I ask my son to get that info for me. It seems obvious to me that my ex does not want to comunicate with me so I am uncomfortable pestering him for more info.