I have a tempstar 5000 high efficiency furnace and the burners ignite and the heat goes on but it is getting hot and the rollout switch is shutting the furnace off and the fan continues to blow until you reset the switch. Does anyone have any ideas what may be causing this. I have had numerous HVAC persons look at it and they haven't been able to figure out what is the matter. One person lowered the gas pressure to 2.5 and it worked then. The fan shut off after reaching the temperature it was set at. The factory recommended pressure is 3.5. Will lowering the pressure cause problems even though it fixes the problem where the switch doesn't shut the furnace down and keep the fan running or is there some other component of the furnace that is causing this problem. If anyone has any suggestions I would appreciate it. Thank you

You have a air movement problem. Make sure all registers are open and the filter is clean with no obstruction on the return air side. It is possible they need to increase the fan speed to compensate for the ductwork that is to small.