talk to him first, for sure, but if he continues to do it or if he's just doing it to be a d-bag and management won't do anything about it, then you can just ignore it as much as possible until you can get reassigned or find another job.
I once had a partner who refused to do anything but drive. Fine by me since I'm a med student and don't like driving (other people were not ok with this), but he also wanted to control all aspects of patient care and tell me what to do and write. After a particularly complex run, he put us back in service when I had 3 run reports to write (yes, with the way the run went, it was technically 3 run reports. One from the facility to the psychiatric hospital, a second from the hospital back to the facility when the hospital refused to admit, and a third generated as we were leaving and the nurse came out to our truck shouting "He went unresponsive!"). Yes, I had to document the hell out of that one. But somewhere between my first and second report, my partner, "got bored" when he was sitting in the truck (I was still in the hospital writing my reports) and put us back in service and came running in to tell me that we had another run. That's where I put my foot down and just flat out ignored him. I was doing the patient care, and I am in-charge until that run is over. Since I'm still writing, the run is not over and if you decided to put us back in service, you'll have to explain to dispatch that we're not actually ready to go on another run yet. He could yell at me all he wanted to in the hospital, it just made him (and the company) look unprofessional and we didn't actually go anywhere for about another hour while I was crossing my t's and dotting my i's. Of course I had to speak to the boss when we got back to the station, but at least the company finally realized there was a problem with this guy. Thinking back, it was probably actually kinda funny to watch; that I was just sitting there sipping on my coke and writing my report while some crazed guy is screaming at me. I was calm throughout the whole thing too, so there he is screaming at me, and me talking to him in a normal tone of voice...