I think at the same time. Once the a/c started blowing the hot air out of the passager side, I then turned the system off. Shorty after turning the system off I notice it was getting hot inside the truck really fast. I started checking it out and notice the hot air coming out of the defrost vents and floor vents. There have been a few times when the system will blow hot air out of drivers side and the passager side. No matter how many times I turn the system off and then back on, it will not correct the problem. If I turn the truck off for a few minutes and restart the truck then the a/c system will correct itself.