Do not spray anything directly on the screen. Spray liquids onto a cloth, and then use the damp cloth to clean the screen. Use water or household glass cleaner. Avoid abrasive cleansers.
If you have a touchscreen, select "menu" then "clean screen". The screen will remain locked for 30 seconds. After 30 seconds press "Done" to resume normal operation. This prevents accidentally changing the mode, set-point, etc. while cleaning.