Qlik Support team answer me with this:
Ajax print PDF with error - Timeout has been exceeded.
When trying to generate a PDF report in Ajax, the error 'Time out has been exceeded' is appearing.
Please try reinstalling PDF X-Change 3 (PDF printer used by QlikView Server)
If you have a multi-server environment, PDF Printer will only be installed on the server hosting the Distribution Service by default.
You can install it manually by downloading the installer from the following link:http://d1cf4w4kkla6tb.cloudfront.net/pdf/9.00/7119/_MSI/QvPDFSetup.exe
(Ensure the Spooler (Print Spooler) service is running before running the installer)
Once done, confirm the printer driver appears in the Devices and Printers applet under \Control Panel\Hardware and Sound\Devices and Printers.
I'll try to do this and, if it will work, I'll mark this issue as solved.