Complete 1 System Lennox HP Split System: HO stated they would set tstat at 68 but system would never cut off when reaching set temp. Cycled system and made sure sequencer and fan relay were working properly. Found bad tstat. It wouldnt cut system off when moving tepm lever down. Replaced it. Used a Proselect non prog tstat from truck stock. Cycled system. System is running properly at this time.