I have a Kenmore dryer model 417.84082500. It runs but does not heat up. I have cleaned the fliter and the cavity where the filter goes. After about 5 min of running the dryer stops and flashes AD. Any sugestions?

You have safety switches that are near the elements that are designed to blow when the drier gets full of dirt and lint. You have to disassemble the entire drier in order to clean it and get to the safety switches. Some of these switches can be reset and others have to be replaced. You will easily see these as they have two wires and are oval in shape with two screws holding it to the side of the tube carrying heated air. Some have one and others have two safeties. You must use an ohm meter to tell if they are bad. If the switch has an open circuit it is bad. There are also thermostats that are wired in series with these safety switches which are used in pairs to tell when there is a temperature difference between the two. They will have a closed circuit so you will find them with the meter easily. The safety will be behind the drum that usually goes out making it necessary to disassemble the entire drier in hopes you will clean it and remove the cause of the problem. Remove all parts and wash them with soap and water. It will be like removing concrete from the walls of the air ducts. Reassemble, replace safety, and you are good for another 3-5 years. It's an easier job than it seems to be. DrTom44