Hi:

I have a 92 Jetta Turbo-diesel with AC (non-functional).

Recently, I have noticed that when I change the air flow control lever to
floor or windshield, no air comes out of those vents. Only the interior 4
vents (2 in the center of the dash and two on either side) have air.

When I change the air flow control lever, I can hear the vacuum servo
working in different selections, but the air is coming from the interior 4
vents only, no matter what the selection on the control is
(floor/windshield).

I read a post in another forum which points to checking the vacuum line from
the brake booster. I have checked all hoses that are under and around the
brake fluid reservoir and all seem to be OK.

Recent work done on this vehicle was front brake pads and rotors were
replaced and brake fluid topped up, now it is above the max mark in the
brake fluid reservoir. The air filter was changed, a coolant temp. sensor
was changed as it was keeping the glow plugs on for longer than required.

What else should I look for? Any suggestions?

Thanks in advance.

There's these vacuum servos. under the dash that switch the doors to the
different vents. I believe you remove the center console and lower
instrument trays to access all of them and you can see them. its in the
Bentley chapter 13- page12. the test is on page 13 to check each vacuum
servo.
"AJ" <amit at interlog dot com> wrote