How to prevent moisture inside the display

Part no: SCHW4250HB-SIP-V1 - Case SCHW4250HB-SIP-V1 - Question: How to prevent moisture inside the display.

Removed the inside air from venting valve in the final installation step.

Step 1:
Unlocked and removed venting valve’s metal cap by #17 wrench.
 
 

Step 2:
Operated vacuum cleaner to remove the inside air from the venting
valve without metal cap.
The step will have 5 minutes.
 

Step 3:
Locked the metal cap immediately and carefully by #17 wrench again.