I have a goodman mid efficiency furnace that was installed in my house in 2007. I have to clean the heat sensor in it about 2 to 3 times a year. I was told by a technician that this is normal for these furnaces. But even after I clean the sensor, the furnace still seems to run all the time (a little less then it does with a dirty sensor). It will run for a few minutes, then it is only off for about 2 minutes until it clicks on again. I had it serviced in the fall and was told that everything was up to par, so why does it keep running? My utility bills are out of control!HELP!