[200q20v] No air from the center vents - problem solved

[Neil Vonhof]

A few days ago I decided to install new vacuum hose to the Turbo Bypass
Valve using Ned Ritchie's (among others) recommendation of re-routing it
away from the engine. Tracing the vacuum hose back from the valve, I
found it was attached to what looks like a two nipple unit mounted on
the very back of the intake manifold. It's very hard to see where the
hose (to the bypass valve) is connected to that double nipple. However,
the other nipple (the one the Bypass vac. hose does not go to) was bare,
nothing attached. Right away I noticed a black rigid hose/pipe leaning
away from the bare nipple with a hose clamp on it, obviously unattached
and obviously belonging on that bare fitting. Sliding this rigid plastic
hose back on the nipple revealed that is was very loose and sloppy and
there would be no way that that rigid hose could be clamped down to grab
the nipple. Looking closer at the nipple I saw a piece of rubber hanging
from it; I slipped it off and realized that it was a small rubber insert
meant to be inserted into the rigid plastic hose so that it could
tighten and seal on the nipple. This rubber insert was torn up and
unusable.  So, what I did was cut a short piece of the 5/32" vacuum hose
I got for the re-routing project (this is inexpensive vac. hose from
Schucks). The 5/32" hose was just pliable enough to allow me to force it
over the rigid hose (with a little Vaseline) and I was able to spread
out the old hose clamp so it would fit over the 5/32" hose to use for
tightening onto the nipple end, with both ends connected, voilà! no more
center vent air problem! What luck! I was close to heading to the shop
willing to fork over too many dollars to have it figured out & fixed.
Nice improvements in idle smoothness as well. This rigid piece of
plastic hose drops straight down (actually has some bends formed in it)
the fire wall to what looks like a little servo or valve or junction of
some sort with a couple or three hoses attached, all going in different
directions. The servo or valve or whatever hangs loose down there, not
attached to the firewall, etc. It's exposed and fairly dirty. So, why is
this hose rigid and not like all the rest of the fabric covered vac.
hoses? Anyway, thanks for all the responses and good ideas. As many
said, a vacuum leak was the problem.
-Neil

Original Post:
Following SJM’s instructions from the web site, I pulled the plenum, and

pulled the passenger side lower dash trim piece and inspected
everything: the return spring, servo mount, vacuum hose connection to
the servo, pivot arm; checked for sticky rubber door seals and
everything mentioned by SJM and it all looks fine.
The symptom is zero air coming out of the center vents, left, middle or
right. Plenty comes out of the far left and right vents on the top of
the dash (near edge of dash closest to the driver) and the defroster
vents and floor vents, but none out of the center vents on any of the
settings (AUTO, Bi-level, Econ, etc.). Also, A/C works just fine.
I don't understand the relationship between the A/C Re-circulation Doors

and the ability for air to blow out of the center vents. With the engine

running, Climate Control set on AUTO, blower on high, with the passenger

window opened, standing outside of the car on passenger side, reaching
under the hood with my right hand I pushed the upper door closed (by the

way, the “default” position now is upper door opened, lower door closed,

all the time) thereby opening the lower door, while reaching through the

passenger window and holding my left hand over the passenger side,
center vent and there was no change, no air blowing out of that vent.
So, should I be checking fuses? Is there more than one blower? Any
ideas?  TIA
Neil Vonhof
‘91 200q20v 128,000 mi