The icon will disappear if the daily temp communication does not occur. You might have a communication problem with the SLW. Turn the SmartLine dial to Advanced Functions / Review / TempData and see if you have high/low temperature readings for the past 5 days. If you have any blank screens, then go to the SLW and perform the diagnostic test as described in the Troubleshooting section of your manual. The SmartLine will also have a missed communication day if the clock time is moved ahead an hour or more (for example resetting for Daylight Savings Time). The icon will return by itself if the controller receives a rain or freeze message from the SLW or if the battery(s) in the SLW have a reportable change in strength. You can restore the icon by holding down on the rain tab on top of the SLW for about 10 seconds.