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Climate Control - Air Direction

vs_berlina

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Hi Folks,
My VS Berlina w/ climate control has developed a strange quirk in that under load (when travelling up hills, or when giving it a bit) the air direction will change from the face to the feet, and back again when the revs and load drops off.
I am aware the system runs off vacuum from the engine, and there are servos that control the direction of the air behind the dash, but wouldn't have a clue how to test them (what resistance should they have for example?) or where to begin troubleshooting.

Does anyone have any experience in this area? I have been quoted about $400~$500 for a new climate control unit, $40 for the servo, plus labour, and I would rather not pay those somewhat steep prices when I can test and hopefully repair myself.

Any help appreciated,
Cheers.
 

gsmrobinson

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check your heater tap befor you do anything...they tend to leak vacuum from time to time. Blank it off and go for a run like that. Also make sure the vacuum lines around the engine do not have a fracture etc in them.

what you are experiencing is a leak in the vacuum side of the climate control. The only way to test is to check each line and block off each servo. Sorry very time consuming.

Regards Guy.
 
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brettkp

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I have had the same problem with my VSII Berlina since buying it almost 2 years ago. Holden replaced a vacuum valve behind the engine 3 times before realising it wasn't the problem.

Another mechanic has tested the vacuum all the way into the module in the dash and said it's all fine (up to the module). I wasn't aware that vacuum entered the module next to the radio. An A/C specialist in Adelaide has quoted $150 just to 'take a look' without any guarantee that they'll find the problem. Needless to say i haven't pursued that option.

Guy, can you provide a little more info on what you mean by blanking the heater tap. (eg how, where is it, what should i look for? etc). I'm not too familiar with vacuum systems and am likely to break something

I've noticed that some days are much worse than others. I can sometimes accelerate 0-100 without a problem, yet other days i won't even get to 60 before it drops to the feet. I quick release of the throttle will return it to normal.

Cheers.
 

gsmrobinson

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Heater tap is on the drivers side on the V6 on the inner guard. It is black and gold/bronze in colour and has either 2 hoses or 4 connected to it and a vacuum line. If you disconnect the vacuum line and blank it off with a screw then go for a drive this will test it the easiest way. On the V8's it is under the cover that sits on the top front of the engine on the drivers side of the engine. You have to remove the 2 covers over the tappet covers and undo the wing nut under the front cover to remove the cover.

Also make sure the vacuum switch which operates the heater tap is working correctly (adjustment of mechanism and/or vacuum leak), it is located next to your left foot as you drive and is either white or black next to the two copper pipes coming through the firewall. Put the vent control all the way to cold and see if the heater tap lever closes then go to hot and see if it opens (the lever at the heater tap should move).....if not see if you have vacuum to the switch near your foot by pulling both vacuum hoses off and seeing which one has vacuum. Connect that one back to the switch and put to cold...is there vacuum at the open fitting ? if yes re-connect the other vacuum hose...if not push the little pin on the front of the switch in. If you get vacuum through the switch now adjust the switch so that its little pin pushes all the way in when the heater flap lever touches it. If it still does not work stick your finger over the open fitting to close it off...does it hiss? if so it is leaking and may be your problem with the vacuum leak replace it, if not and you can't feel a vacuum at all it is blocked and you will have to replace it...but it won't be the problem...sorry. PS do this test with the engine running.

Hope I have not confussed you too much...too tired to think....sorry

Kind regards Guy.
 

Darren

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Very interesting indeed. My sisters car has recently started doing the same thing. I thought it was just her imagination since she doesn't even know how much oil to put in.

When she hits about 90kph the air goes from the face straight to the feet.

This is the switch based stuff ie not climate control so I may have to check a few things out when I get a chance.
 

gsmrobinson

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On the standard systems the vacuum switch behind the controls leaks and can cause the same problem....if all else is OK replace it about $30 from holden.

Regards GUY.
 

markovr

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I have seen a bloke try to put that vacuum /level control knob off by grabbing it (probably trying to take it out so he can put a new stereo) in and this brakes the tang on square drive on the mechanism that locks everything together and the pressure is relieved on the vacuum director on the level control.
It works ok at small vacuum but as the vacuum rises it lets the vacuum past.Once the seal is broken it lets it all go and there is a pronounced hissing noise at the switch.How the vacuum hoses plug up to the unit is a bit finicky too.
The doors on the heater /ac box are vacuum controlled once the vacuum is lost the doors go back to the position they were at rest .
This is just an experience I had once


Mark
 
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brettkp

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It's finally fixed!!!

I went to a holden dealer the other day and they tested the whole vacuum system. For me it turned out the one of the vacuum solenoids was leaking. There are 5 in one module. They didn't have the part in stock. They gave me the number (92140248) and i picked one up the next day ($100). Took about an hour to install myself. It sits below the radio/console so taking all those panels out will reveal all. It's a bit awkward to put the new one in, but not impossible. Add another 30 mins to replace all the panels (and in my case fix the cig lighter - i pulled a wire out) and you're done!

Haven't had a problem since. I pulled the old vacuum solenoid module apart and had a look at it. There's no visible sign of one of the solenoids being leaky, it could be a slightly warn o-ring or one of the plungers may be a bit warn.

In my case i noticed a clicking sound when accelerating and a similar (but reverse - if that makes sense) noise when decelerating. I think that had something to do with the faulty solenoid cause i haven't noticed the same noise since fixing it.

Of course, there's no guarentee that it's the same problem on your car. It cost me $80 for the diagnosis. I guess if it's just a hose it'd be a lot cheaper to fix.

Hope that helps.

Brett.
 

Frederick

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I've just had the same with my VS Statesman. The top duct is held open by vacuum and the feet duct is held closed by vacuum so if there is a vacuum leak then the top duct closes and the feet one opens. The problem appears during uphill or high trottle conditions because engine vacuum is then insuficient to overcome the leak. On mine I had to clean the vacuum valves below the radio, these can be opened and the rubber seals cleaned and the valve blown thru with compressed air. I still have a very slight leak where the hoses plug onto the vacuum valves, need to seal this with something that cab be removed if necessary, other than silastic, any ideas anyone? Also the check valve at the rear of the engine also seems the leak a little when the engine is running and the pressure difference across the valve is small. With engine stopped the valve seals OK so I may need to replace it. Hope this helps
 
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brettkp

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A friend of mine suggested using vaseline around the seals. Don't know if it'd be good or bad though.

I've had the valve at the rear of the engine replaced (wrongly) a few times - they're pretty cheap to replace i think (<$30).

Brett
 
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