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Center vent vacuum issue?

1K views 10 replies 6 participants last post by  The donut man 
#1 ·
Hey everyone -- minor problem; not sure if it's vacuum related or what.

For the first 15-20 minutes after I turn the car on (before it really warms up) and I'm running the AC, the center vent turns off when I press the accelerator, then turns back on when I lift off the pedal. I can actually hear the flap closing every time.

That behavior stops after the car warms up, but at that point the center vent won't turn off at all, regardless of whether the blue/red buttons are on or not. Other than that, climate control function seems to be normal.

Like I said, not sure if this is vacuum related or something else. Any ideas?
 
#2 ·
Only thing I can think of is blower regulator, but that's such a bizarre behavior. If it was off all the time I'd say it's a certain hose.. If you have a spare regulator, it'd be nice to try out.
 
#4 ·
How is your door lock pump working?

Lumbar working?

The passenger kick-panel is the main trunk for vacuum on most W140s. The grey manifold there can break. Run a quick smoke test with 4 of July Punk, or a incense stick, orrrrr if you smoke-blow smoke on it

If a the doorlock pump breaks at the tip nipple on the vacuum feed line it will do this. I chased one of these problems for a year as I too had the same problem...

Here is another one. I encountered this one too.. One plugs one line on the doorlock pump(I cannot remember which line-bad me) it will do this, so.... if you had some work done, on the locking system. Make sure the lines are in the correct location...

The manifold distribution block is usually(behind the glove box) solid, but rarely fails.

All the best,

Martin
 
#5 ·
The plug for blue or red switch is the same as the glove box light...made that mistake before.

Run the flap test and listen for the hiss........ Fixing the known offenders usually repairs the lethargic reactions in the system. Door stuff for sure....lock control and close assist....then it's the lumbar switch...trunk junk...then everything starts working like magic.

the door connection red and yellow lines have that plug at the kick panel also....does anyone have a vacuum schematic for these systems....the entire system?
 
#8 ·
Vacuum controls the blower for the air? My pump recently broke and I don't really have the money to drop if it's unnecessary... Med school apps are really expensive :frown

I can live without locks etc., but not air :wink
 
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