I'm not sure what you are describing according to the details of your question. According to your model number, I am showing one temperature switch that provides either heat or air dry settings. If the dryer heats up the first time and then does not cycle back on to maintain the proper dryer heat, then you could have a failed operating thermostat. On the heated setting, this thermostat will normally cycle the heating element on and off around 150 degrees F. If the dryer is not cycling properly, this could also indicate a bad thermostat.
I would need more details concerning your dryer problem to be able to help you resolve this heating issue. Resubmit your question with more details if you need more assistance with this heating problem.