Sorry no model or serial no. Unit serves 20x20 server room, very light load, only 2 small server racks. Sensor is located at about 7 feet elevation immediately to side of walk in door. I have replaced the sensor circuit board. This unit has been in service about 5 years and this problem just recently occured and it has been driving me nuts. I get a big swing in humidity. Set points are temp 70 w/3 diff, rh 45 w/4 diff. I'm even starting to get mold occasionally near the liebert. The wall the unit is mounted to is common to a large maintenance shop which is non conditioned, although it is insulated it does not have a vapor barrier. We are having 90 degree days and 80% rh quite frequently, also shop overhead door is typically open. I'll typically check unit stat a couple times a day. Sometimes I'll have as high as 85% rh . As soon as the unit starts to dehum rh will drop 5% a minute but by the time the rh drops to set point room temp will also drop to low 60s bringing on the heater. Unit's charge is good. Are my parameters way off? Yesterday I disabled the humidifer and set temp @ 69 degree with no diff when I left the site to see what would happen over the weekend. Any suggestions?