I am guessing you mean a thermostat and a thermometer (thermometers read temps and thermostats control temps) . Keep in mind racks don't hold huge amounts of temps so typically room temp plays an important part in the cool side and ambient air temps. Personally I find that is a room at or below 'normal' 68ºF the cool end and air temps are below what is common thought as acceptable. (mid 70s) the easiest solution is to heat the room to a higher temp (most whom choose this method use 80º or so) Some choose a secondary heat system to add heat to the rack to help hold the temps (less power more start up costs) I mention this just in case you have heating issues.