I have a new Frigidaire Dryer (model number FEQ332ES) and after it's 3rd load (drying undergarments on medium heat) the top back of the dryer became very hot and the dryer started to make a bumping noise (it sounds as if something such as tennis shoes are in the dryer). I checked the ventilation and it seemed to be fine. Although when the dryer was first tested there was more air flow (maybe since the dryer was empty) and when I checked the air flow when the dryer had clothes in it the air flow had decreased. I tried the dryer empty and it still made the bumping noise and the airflow was not as intensive as it originally was.
I'm not sure where to go from here... call the manufacturer, etc.
Thanks for your help.

I had a similar problem and the first thing the serviceman asked was if I used dryer sheets. I thought this was odd, but he explained that the sheets produce a wax which builds up on the lint filter and restricts air flow. The filter may look clean but you might try running it under some water in case there are any clogs. Also dryers can get hot if the vent is clogged.