weird a/c sequence

[ianb]

hi
i have a problem with the operation on my vt berlina series 1 air /con
when on face mode it goes to windscreen mode when you accelerate
when you back off it comes back to the face mode
i suspect that it is a vacuum problem
trouble is that i have only had the car for a month and i am not familiar where these things are any help would be great
thanks
ian b

[accentstencil]

Sometimes, under heavy acceleration, it is normal for that to happen. Often when there is a vacuum leak the main culprit is the thin vacuum hose that goes to the rear of the intake manifold. There is also a plastic valve thing connected to it that may not be working. The vacuum tank is up behind the glove box.

[ianb]

Sometimes, under heavy acceleration, it is normal for that to happen. Often when there is a vacuum leak the main culprit is the thin vacuum hose that goes to the rear of the intake manifold. There is also a plastic valve thing connected to it that may not be working. The vacuum tank is up behind the glove box.

thanks for that
it gives me somewhere to start looking
cheers
ian

[Doctor Bob]

its not normal under any circumstances.
it is caused by a vacuum leak or lack of vacuum to the actuators.
check the one way valve in the line under the bonnet, it can also be one of the actuators in the dash or a crimped line in the dash.

Rob

[accentstencil]

I'm sorry for providing the wrong info on it "sometimes being normal under heavy acceleration" but I thought I got that information from a reliable source.
Once again I am wrong.

[Aus78Formula]

Ian,
Did you get this sorted? My 98 VS does the same thing, especially under load. It came back from the AC/ electricians unfixed so unless he has some ideas in a hurry it will be going elsewhere this time.
Ben

[Doctor Bob]

if it happens in floor mode as well the vac leak is in the supply circuit, if its only in face mode the problem will most likely be the actuator.

[Aus78Formula]

Helpful info Bob, I think it's to the floor as the redirected air isnt that obvious, rather just the on and off of the face air. Will check, thanks.

[ianb]

Sometimes, under heavy acceleration, it is normal for that to happen. Often when there is a vacuum leak the main culprit is the thin vacuum hose that goes to the rear of the intake manifold. There is also a plastic valve thing connected to it that may not be working. The vacuum tank is up behind the glove box.

thanks for the help guys
you were right accentstencil , it was the thin rubber line behind the inlet manifold
for some reason the rubber hose had swollen, and it was not sealing properly
luckily there is ample length there to cut of the end and fit it back over the nipple , all works well now
ian

[Aus78Formula]

I checked the vacuum hose out of the rear of the manifold of my SC V6 and it seems fine, no cracks or swelling. Now the line splits off, one goes through the firewall and to the controls etc I assume, the other line wraps right around the engine bay edge and disappears down near the headlight. Where does that vacuum hose go? Also, theres a white one way valve looking item on this line, a bit like the valves on the washer nozzle hoses. If this is letting vacuum back through the way it came would it affect the air vent operation? This is still the line that runs off to the front of the car so not sure what it operates and none of this setup is in the standard Gregory's VS manual due to it being a SC motor.
any ideas?
thanks
Ben

[accentstencil]

The hose near the headlight is probably going to the vacuum tank. It that valve is not working it will cause problems.

[Aus78Formula]

Thanks I'll look into this valve and if it may be faulty. Would it have a direct effect on the vent operation as no other hoses appeared faulty or squashed, even had electrician go over it chasing ideas.