Just installed two trane xl units. The problem I have is when I call for a certain temp on the tstat if I do not do it in one degree increments it never reaches the set point. And, at times if say the room is 75 deg. and I ask for 74 deg. the tstat will shortly show the room temp going up, to 75. What gives? One day the house was 77 deg. I asked for 74 and it ran all day and never dropped a degree. Very frustrated with this system.