In October we replaced our entire air/heating system. It has worked perfectly until earlier this week when the weather got extremely cold. The outside unit began to vibrate and make loud banging noises, so we shut it off and called Rosenberg which had installed the unit. A nice man named John took the call and advised that we would have a tech at our house between 10:00 and 2:00. Rosenberg tech Derrick Rogers arrived around 10:30 and quickly discovered the problem. He advised me that a part was needed and went to pick it up. A short time later he came back re-assembled the outside unit and tested it for several minutes, and it worked beautifully. Mr. Rogers was pleasant, professional and easy to communicate with. His worked was done right the first time, and we are very appreciative of his efforts. Thanks to Derrick and to Rosenberg for the excellent service.