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Calais climate control on 'AUTO' throws to demister when uphill grade ?? vacuum issue

Trent L

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Hi VZ Calais 190Kw 10/2004.

40C day with climate control aircon on 'AUTO'. When you come across a reasonable uphill gradient cruising about 1800rpm the aircon shuts off and vents throw up to demister, blowing 40C directly into your face. Happens at lower speeds to.

As soon as the gradient levels back out the aircon resumes as if nothing happened.

Obviously a vacuum leak issue, so I checked the vacuum line at the back of the engine & the one way valve seems to be working.

I'm not a plumber, so where do I start looking now? I know there are a lot of vacuum hoses behind the glove box & deep inside the dashboard.

Can anyone give me the next most likely suspect and where to start looking please?

Or is this a hit & miss Holden Dealer job at $$ per hour. Out of warranty :(
 

starkeyholden

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I noticed this myself (VZ Adventra) on a 40 degree day about 2 weeks ago, same thing happened at anything more than moderate acceleration, hot air from windscreen vents. wasn't really dependent on uphill/downhill. Hasn't happened before or since that day. Although now i notice that when i have the AirCon on, the 2 vents in the middle of the dash blow warmer air than the other ones. (It may have always been this way and I am only just noticing). Will have to try again next hot day and see if it happens again. Good luck with it, and sorry I couldn't help much.
 

Trent L

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Symptoms worsened over the weekend so vehicle delivered to Holden Service Centre.

Now at day 2 (as part was late to arrive on day 1). Vacuum actuator replaced.

Took it for a test drive but aircon still throwing from vents to demister mode on uphill grade, with light depression of throttle when vacuum drops.

Let's see what Day 3 brings.
 

Trent L

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Car came back today after a week in dry dock.

Fault detection with a a vacuum pump took a while and the Calais ended up with half the dash removed to find the fault. Culprit was vacuum actuator part no. 210904451 that sits up near the heater box. The part has two diaphragms and one of the two was not sealing.

Couple of hundred to fix but back to normal just in time for a 39C day!
 

starkeyholden

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Hmm, mine goes in tomorrow morning, I'll make sure to point them in that direction first, see if it'll save them a few hours of searching for the problem.
 

FnomnaVZ

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Just thought I'd throw in another possible scenario for anyone with the vent changing problem.
My original problem was this
http://forums.justcommodores.com.au...acuum-tube-vz-alloytec-motor.html#post1505215
Basically I thought they just put the black/white valve on the wrong hose.
It was:

TOP firewall vacuum hose -> white-black valve -> heater tap actuator
BOTTOM firewall hose -> vacuum port on engine inlet manifold

So I changed the valve (position and back-to-front), so:
TOP firewall vacuum hose -> heater tap actuator
BOTTOM firewall hose -> black-white valve -> vacuum port on engine inlet manifold
Nothing seemed to change when I did this.

I finally figured mine out today after looking through all the threads on here about it. I found the diagrams very useful:

Solenoid operation
http://forums.justcommodores.com.au...s-climate-control-diagonostic.html#post945785

HVAC vacuum system diagram
https://forums.justcommodores.com.au/threads/vt-climate-control-vacuum-problem.109191#post1244963
(On my VZ the heater control hose is yellow at the solenoid pack, not black)

Vacuum solenoid pack
https://forums.justcommodores.com.au/threads/vt-climate-control-vacuum-problem.109191#post1245764
(On my VZ the round foam ports are facing down)

My problem was this:
* I normally set the climate control at about 25 deg on AUTO.
* All vent directions worked ok if I pressed MODE.
* I noticed what seemed to be random changing of the vent to WINDSCREEN and it would stay there.
Yesterday I realised this would happen when the cabin temp had reached 25 and the system wanted to open the heater tap to blend warm air and keep it at 25.
If I lowered the temp to say 22, the vent would go back to the FACE position as it wanted to close the heater tap.
* I could see in the engine bay that when the system wanted to open the heater tap, it would stay closed. If I took the vacuum hose off the heater tap, it would lose vacuum and open the tap. This seemed strange that vacuum would be held.

Last night I took out the solenoid pack and was looking for bad solder joins, but all seemed ok apart from a couple of brown ones. There wasn't excessive dust on the foam. I did notice that on the acrylic connector with all the coloured hoses on it that attaches to the pack - the yellow port looked a bit brown, like oil stained.

I put the pack back in to the car and started her up. This time I took off the two vacuum connectors that go to the solenoid for the heater tap. Then it clicked.
The black hose is meant to supply vacuum to all the solenoids. There was no vacuum at any of the supply connectors on the pack.
I noticed there WAS vacuum coming FROM the yellow hose. This was definitely wrong. Vacuum was meant to be appied TO the coloured hoses.

So I looked at the system diagram and realised the heater tap vacuum hose and the vacuum supply hoses were swapped in the engine bay. I swapped them and everything works fine now!!!

So now it's
TOP firewall vacuum hose -> white-black valve -> vacuum port on engine inlet manifold
BOTTOM firewall hose -> heater tap actuator
Can someone confirm this is the same as on their engine??? VZ, but VT-VY may be the same.

(It seemed very strange that even though these two hoses were swapped, all controls seemed to work ok for the vents - except when the system wanted the heater tap open.
Now I understand what was happening:

* Cabin above 25 deg:
* Vacuum supply was connected to the yellow hose.
* That solenoid (for heater tap) was ON (wanting to close the heater tap by supplying vacuum to it), connecting the yellow and black ports.
* The black line was connected to the heater tap, vacuum present, heater tap closed
* This meant now there WAS vacuum on the black line for all the other solenoids - thus why they still worked!

* Cabin reached 25 deg:
* Vacuum supply on the yellow hose.
* That solenoid OFF (wanting to open the heater tap), connecting the yellow port to the foam vent.
THIS NOW MEANT VACUUM LEAK to the foam vent. But I could NOT hear this leak at the foam?!
* This meant loss of vacuum supply to the other solenoids - resulting in vents to WINDSCREEN - the default position when no vac!
* The black line connected to the heater tap was now on the closed port of the solenoid, thus why vacuum was held to the heater tap.)
:surprise:
I thought I'd contribute this in case anyone's always had this problem - maybe someone just put the 2 vac lines on the wrong way in the engine bay!


WHY DON'T THEY JUST MAKE THE SYSTEM ELECTRONICALLY ACTUATED INSTEAD OF MUCKING AROUND WITH VACUUM ??!!!
 
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Trent L

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And apparently that was the solution they employed in the VE model.

Electrics instead of vacuum.

Shame components of the system aren't interchangeable VE to VZ to overcome the issue.
 

br4dlz

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hey guys, what my mechanic did to fix this on my VZ adventra, was to get another actuator, and run them together, as to double the amount of vacuum being held. not a perfect fix but it hasnt done it since....i imagine it would do it on a MASSSSIIIVEEE hill but for my area (eltham which is really hilly) it works fine :)
 
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