I currently have York Diamond 90 series heater. We have been having problems with getting our modest size home heated. The home is only 5 years old and we can't seem to get the temperature above 70 degrees. We often notice the heater running, sometimes for hours, with little or no heat coming out. I just checked the furnace and found the burner to run for about 5 minutes, before it shut off and the blower continued to run. The trouble shooting light blinked (4) times, and the reference stated it was an Aux. overload/Spill over??? This HVAC system has been a nightmare for my family. The original builder had to come out 22 times to get the system to somewhat function properly. Any ideas of what I'm looking at before some new HVAC company comes out and tells me I need a whole new system?