Vents change up hill

[Fettler]

I have a VY Berlina. When I go up hill the air vents change from face to screen. It seems like a vacuum issue but all the hoses are connected. Any ideas?

[Boonz]

ive seen it once at work, i think it was the hot air mix flap actuator leaking.... so it could be one of the actuators in the system...theres 6 or 7 from memory

[davey g-force]

I've seen this one covered before here somewhere, so it must be fairly common. I can't remember the outcome though. Have you tried doing a search?

[ris00]

it is normal took mine to holden they said its normal, got something to do with the vaccuum cant get enough pressure or something to keep the vent open so it opens the default vent which is the windscreen one.

[davey g-force]

it is normal took mine to holden they said its normal, got something to do with the vaccuum cant get enough pressure or something to keep the vent open so it opens the default vent which is the windscreen one.

Hmmm, that sounds like a Holden dealer cop-out to me...

Maybe they're right, but I'd be looking into it more.

[shaggerz]

I know its not VS but all the climate control systems up to VS and probably onward have an issue where occasionally when going uphill the vents change from face to floor, and return to face when you get off the throttle.

My understanding is that this is normal because of the way the vents are controlled. I am guessing its because under those engine conditions, there is not enough vacuum being stored in the vacuum ball to maintain adequate pressure at the air vent servos, and they return to their default positions until the engine conditions change and the vacuum comes back.

[50LTRv8]

I have the same issue in my VT. I did have this issue in my falc and there was a vacuum hose connector that had come loose. I just can't find the same sort of thing in the commie

bugger

50LTRv8

[Utester]

The problem will most likely be the one way vacuum check valve (it is black and white) in the engine bay near the firewall.

[Degeko]

i have same problem, found the vacuum tank under the passenger airbag and its too small to hold enough vacuum for the system (design fault) im putting another larger canister under the bonnet to increase capacity, hopefully that will help.

[my03equipe]

I had a Berlina VS II, Did the same thing going up hill. Had it checked out, nothing to worry about has something to do with the climate control system. I never had any ongoing issues as a result til my wife wrote it off.

[whitey66]

i have same problem, found the vacuum tank under the passenger airbag and its too small to hold enough vacuum for the system (design fault) im putting another larger canister under the bonnet to increase capacity, hopefully that will help.

The size of the vacuum tank is not a design fault at all.
Putting a larger tank on it will only mask your faulty leaking vacuum system.
It is not normal for this to happen,it's caused by a loss of vacuum in the system.
As mentioned above,check the one-way valve at the inlet manifold,check the vacuum actuators under the dash that control the mixing doors.If the one-way valve is OK,the second most likely cause is the vacuum actuators.They get a hole in the diaphragm and don't hold vacuum.
To diagnose these properly you need a vacuum pump/gauge and knowledge of how the system works.

[qector]

Easy to fix,tried bigger tank, if it worked on leaving the factory it should be easy to fix. The vacuum cylinder under right side of console needs replacing, did mine and no more trouble. Qector

[aaronevolution]

My VR, VY, VZ and my brothers VT, VU and VZ all do this. Surely your not saying there is something wrong with all of them? I'm pretty sure it's normal. Nothing to worry about.