Technician reported an improper windshield change lead to aircraft's inability to pressurize.

Attributes
ACN	1700395
Time
Date	201911
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Pressurization Control System
Person 1
Function	Technician
Qualification	Maintenance Airframe Maintenance Powerplant
Person 2
Function	Technician
Qualification	Maintenance Airframe Maintenance Powerplant
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy Deviation - Procedural Maintenance

Narrative:

Aircraft was leaving from ZZZ to ZZZ1 and aircraft did not pressurize. Crew returned to field. Aircraft was in maintenance overnight with a double windshield change which requires [aircraft] to be pressurized to verify no leaks. Manual switch on the avionics ventilation overboard extract valve was missing labels for on\off position. Add perform a bite check of the avionics extract fan ventilation system; to verify proper operation of closing and opening of the valve.

Original NASA ASRS Text

Title: Technician reported an improper windshield change lead to aircraft's inability to pressurize.

Narrative: Aircraft was leaving from ZZZ to ZZZ1 and aircraft did not pressurize. Crew returned to field. Aircraft was in maintenance overnight with a double windshield change which requires [aircraft] to be pressurized to verify no leaks. Manual switch on the avionics ventilation overboard extract valve was missing labels for on\off position. Add perform a bite check of the avionics extract fan ventilation system; to verify proper operation of closing and opening of the valve.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.