Air distribution problem (omega)

The rotary switch for the air distribution has stopped working on my Omega
2.5 v6 1998. It only blows on windsereen now where ever the switch is turned
ie nothing from air vents or to the footwells.
If anyone can help with this problem I will be very grateful. I have a
Haynes manual which says these functions are vacuum operated by a unit
behind the glovebox somewhere but before I start tearing the car apart as
all functions are gone I`m thinking the main vacuum feed to this unit must
be disconnected somewhere.
The car recently had a water leak repaired -it was the plastic valve for
the heater hoses which also has a vacuume hose connected. Been back to them
qnd they they say the problems are not connected. I only noticed the air
distribution switch not working after they replaced the valve. Could they
have left a vacuum hose off somewhere?
Anyone got any ideas where to start .Thanks in advance,
regards, Michael

 

Start it up and listen for a hissing sound either in the car or under the
bonnet. If a pipe is off you will soon find it.

 

yes they could of left it off or pulled it.
you should be able to detect it by listening.
it should make quite a racket

mike

 

Thanks guys. I have indeeed found a vacuum pipe disconnected. I cant see
where it goes though. So it back to the garage now demanding they put it
right foc.
regards,
Michael

 

There should be two small black pipes coming out from the centre area of the
bulkhead. One of these pipes (Normally shorter with a small white band on
the end) connect to the top of water valve (tight against the bulhead) the
other pipe connects to a small stub (normally at the non-return valve)on the
large black hose that leads to the brake servo.

Check these are connected.

Steve

 

I've got the same symptoms and have found that if the temperature
controls are both wound all the way to the left (i.e. fully cold) then
air only goes to the windscreen but if one of the temp controls is
moved clockwise by even one notch then full control is restored.

Gonna start looking for loose hoses on Saturday ....

Regards
Steve G

 

I too have had this problem for some time now on my Omega and have checked
all the vacuum pipes etc to no avail. Any other ideas?

 

Thanks for that Mike. Thing is I've checked all the vacuum pipes and
everything seems ok. It's been a problem for a while now, perhaps I'll gety
it looked at.

 

The rubber distribution block at the back of the control knob kept
falling off on mine for some reason. If I remember correctly it's an
oily type of rubber so you can't stick it on as such. When the engine
is running the vacuum holds it in place and I just tied mine close
somehow to stop it dropping away, can't remember how I tied it up now,
I think I put a tie wrap over it and the edge of the board - I remember
not being convinced that was the problem or if it would hold, but I've
not had any problems since.

 

I have also had all this apart as you could hear it ocassionally hissing. I
also put some silicon grease around it to try to seal it but although it
seemed to improve things for a short while it stopped working again shortly
after.
Again thanks for the info

 

That was just enough to trigger my memory Paul

It was the hissing that directed me to it and I didn't tie it up. My
symptoms were that it wouldn't switch things very well until I had been
driving a while, presumably the vibration and vacuum pulled it in
enough to seal. Funnily it always worked when the car went in for a
service...

I put a thin layer of silicon sealant around the base of the 'spikes'
and left it overnight to go off after putting it all together, didn't
want it to be sucked in and block the pathways.

I did have to open it up again the next day because I had knocked the
cable off one of the temperature knobs and the block fell off, that's
how I know it didn't stick it in place. I put it back on and it's been
fine ever since.