HVAC vacuum system

[Yoni_d]

Hi All

Since I have a problem in some of my flaps, I would like to perform the test that is written in the workshop manual in page 87-108.
The test checks the flaps position program.

I dont understand the "Testing Preconditions"...maybe because of my English

1) "Switch ignition on" - does it mean start the engine or only to switch it to the "on" position?

2)" Vacuum system must be leak tight and depressurized" - what does it mean depressurized? if the engine is not working - then there is no vacuum in the system so if this is called depressurized system, how can the flaps work? or depressurized means that the system must be with vacuum using some sort of external vacuum pressure from an air compressor for example if the engine is not running?

3) open central vent - understood

I would be happy if someone will clear this issue for me