I have a Whytner 251s cigar cooler and really Luv it. When I set it up I called Whytner and they said just follow the directions and do not add fans, or gadgets, the cooler is designed for cigars as is. I wiped down with distilled water, seasoned the drawers and shelves lightly with a sponge with DW, let dry completely and installed. Put distilled water in the bottom tray and plugged in for a day, I installed my digital hygrometer right in the center added 65% Bovedas, 2-3 per drawer/shelve. Added cigars that were seasoned at 65%, after two weeks removed the DW tray and itís done. I don't worry about what the temp is from bottom to top. All my cigars smoke great. Temp 63 deg, RH 65%. The great thing about a cooler is you can unplug and it becomes an air tight humidor maintaining perfect humidity. I do a rotation of cigars about every 3 months from top to bottom. Several months back I went to all drawers for more storage ability, used same principle and worked perfect.
Once I did have to add some KL when the humidity out was terrible! The geographical areas across the US and where the cooler is stored makes a huge difference so whats good for one person isnít good for the next. I have my cooler in my basement which is a plus. Room temp is important.
Keep the temp down and RH between 61-65 % and your cigars should smoke perfect. When frustration becomes overwhelming, go to Tupperware with bovedas 62 or 65% air out on occasion and start over with the cooler from scratch. This is of course just my opinion but this is what has worked for me. I have 3 tuppers now and never checked the RH, just added cigars with bovedas and no issues.
Hope this helps a little even though I didnít directly address your question.
US Army Veteran 1974-1985