Service on Minisplits

Hi, I installed 3 mini splits that are serviced by one heat pump that’s installed in my backyard. I live in Windsor Terrace. Two of them work great, one of them blows only cold air. My contractor and I don’t agree that there is a problem. Can anyone recommend someone that I could pay to evaluate the three units and a) tell me if there’s a problem, and maybe b) offer solutions. Thank you in advance. They are Daikin units.