Hi. I need some advice. My husband and I moved into a new construction house in January 2007. We have a 1600 sq ft colonial on a slab. Our hvac is a single stage Goodman. When we would run the heat in the winter I kept it at 73. The downstairs was comfortable but the upstairs was bone chilling cold. From what I understand on a slab it is a bit colder than if having a basement. I had the company out that installed the system and they recommended better weather stripping for the windows..which we had someone out to do. We even put the plastic on the windows which helped a tiny bit..but we still had to dress very warmly for bed. Now that warm weather has arrived we have had to turn the air on. Now the problem is just the opposite. It is cool downstairs but very warm upstairs. I do expect a temperature difference but it seems very extreme. I have the thermostat set at 70 just so the upstairs is comfortable enough to sleep in and it is still very warm. The minute you walk up the steps you get blasted with warm air. Am I doing something wrong or should I gave the company back out to take another look. I know there should be a temperature difference but it seems so extreme. Any advice or ideas?