I have had numerous problems with this system.I had changed some old registers during remodeling but never touched the controls.I wouldn't even know how to.I have noticed that after my annual service cleaning is when the problems arise.Last year the parameters of the controls were changed back to factory specs durning this service.Your service person came back and readjusted them and everything was fine.I have suggested that the service person leave the parameters alone during the annual cleaning.these adjustments have taken too long to be changed back to factory specs,which start my problems over again.