1990 ls400 heater contols

[1990 ls400]

I know about the LCD problem but I also have another concern, I have no temp control......all the way cold gives me cold air but as soon as I go 1 click up on the temp it goes all the way to full hot. What I am truying to say is there is no in between. I get cold or hot, no warm air, so I freeze or sweat, no happy medium, any help would be greatly appreciated..Is the a calibration proceedure???? Thanks...