A/C issue under acceleration

[kyefs]

Hi guys, new to this forum and this has probably been addressed in a previous post but I don't have all night to search and I couldn't find anything after a bit of a look so hoping someone can help...

I have a VZ Calais, A/C works fine when I turn the car on and whilst at speed with low revs but whilst under heavier acceleration and taking off at lights when it gets to about 40kms (still accelerating to anywhere between 60kms and 100kms) the airflow stops coming out of the vents and appears to blow up against the windscreen as if I had the front dimister on. Doesn't appear to actually send any cold air there though and when it's boiling hot and I need the A/C, I pretty much have to take my foot off the throttle and wait a second til it starts blowing out the face level vents again, then go again.

If anyone knows how I can fix this myself, I'm capable of taking apart a car and putting it back together so no issues there, just have NO idea what I am looking for or what part I need...never come across this issue before???

Thanks in advance

[derrro]

Hey here's what I think.

A little while ago I was mucking round in my engine bay I accidently disconnected the vacuum hose to the HVAC climate cntrl unit. What this did was not provide the unit with any air suction, and by default the climate control reverts to demist (perhaps it's a design thing to make sure u can demist if the unit loses pressure or just a fluke?).

So what it sounds like is that when you accelerate the vacuum pressure drops off to your climate control HVAC box. So:

1) Check for lose hoses under the bonnet
2) Failing this check the vacuum hoses are properly clipped up to prevent movement
3) If all ok, disconnect the hose going to the HVAC. Lick ur finger and put it over the end of the hose (on the engine side) to test for a vacuum. Get someone to rev up the engine and check for consistency of pressure.

There is a vacuum cylinder somewhere in the car (inside the cabin maybe). This is to make up for the natural loss of vacuum when the engine revs harder. You might want to look up where this is and check that too.

[dfer]

kyefs

A/C issue under acceleration
Hi guys, new to this forum and this has probably been addressed in a previous post but I don't have all night to search and I couldn't find anything after a bit of a look so hoping someone can help...

I have a VZ Calais, A/C works fine when I turn the car on and whilst at speed with low revs but whilst under heavier acceleration and taking off at lights when it gets to about 40kms (still accelerating to anywhere between 60kms and 100kms) the airflow stops coming out of the vents and appears to blow up against the windscreen as if I had the front dimister on. Doesn't appear to actually send any cold air there though and when it's boiling hot and I need the A/C, I pretty much have to take my foot off the throttle and wait a second til it starts blowing out the face level vents again, then go again.

If anyone knows how I can fix this myself, I'm capable of taking apart a car and putting it back together so no issues there, just have NO idea what I am looking for or what part I need...never come across this issue before???

Thanks in advance

I'm having the exact same problem mate. I have no idea what's causing it, but as suggested above I will check it out but somehow I don't think thats the problem.

[magnetvh]

Easy fix mate. Could b like the 1st guy said but I rekom It's the heater tap. Under the bonnet near the fire wall is whr you'll find it. There r 2 or 3 vac hoses on it and a medium coolant hose going in and comin out. If 1 of those vac hoses comes of or is damaged it sends the a/c up the windscreen under acceleration. If the tap is farkd, U can pick em up at your local auto shop like supercheap or somethin. Costs around $40.

[Trent L]

Ah if only it were that simple. It could be the one way valve - but if not - check the below links.

I have been there before (exactly the same issue) and it was a vacuum requiring removal of the dash & replacement of actuators - and yes it is a drama.

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

VZ climate control issues!

Hope yours is the cheap option!

[Tom]

Hi Kyefs,
have just joined the forum,and have the same problem as you, I heard from someone today that the flaps inside are controlled by vacuum,
and it may be a leak in the system, there is a valve on one of the small hoses (approx 5mm dia), around the external of the air intake box, which is supposed to be at the back of the engine bay,( maybe or behind the dash), it might be fitted wrongly or there is an air leak somewhere on one of those tubes, anyway give it a try. I am working away, and unable to get to my car for about ten days so can you let me know if it works, or if its something else?
Thanks Tom

[Tom]

Hi trent, or anybody that can help, I have the same prob as the other guys, and as you have been there before are you able to give me some info on;-

1 what part of the vac system can be reached from the engine bay?

2 What parts of the dash do I have to remove to get to the actuators?

3 I would be grateful for a bit of a detailed description, on the order in which I remove the dash bits, and any tricky bits to get to,

as I tend to get annoyed when I cant find the screws etc, for the next section to be removed, and I have been known to resort to

some over the top weaponry, such as:- small hacksaws, big hacksaws, small hammers, big hammers, sledgies, angle grinders, oxy sets :-),

any help would be appriciated, Tom.

[bcw61]

I have been there before (exactly the same issue) and it was a vacuum requiring removal of the dash & replacement of actuators - and yes it is a drama

Fortunately you can change the vacuum actuators without having to remove the HVAC unit, or most of the dash. I had to replace both the face & foot actuators on my VZ. The foot actuator can be replaced by working from within the drivers footwell area. The face actuator is a little more difficult to replace, as you need to remove the centre console & central part of the dash (including the area underneath the headunit), to gain access. The vacuum hoses to the face actuator can be accessed via the passenger footwell area. It is a bit of a contortionist act to replace them, but I'm not exactly skinny anymore, and managed to replace them OK. Its far better than the recommended method of removing the HVAC unit in toto.

Access to the fresh air/recirculation actuator is by reaching up from within the passenger footwell area.

[Trent L]

bcw61 has pretty well hit the nail on the head.

The only part you can reach from the engine bay is the one way valve near the firewall. If that is functioning then its under the dash you go.

Hope these attachments are of some use.

[Tom]

Hey Trent thanks for the effort you went too to put the info from the manual online.

hope we can help you sometime, Tom

[fangios]

Hi all,

I too have this problem with my VZ berlina wagon. I will try and start doing some investigations using the above info, if anyone finds the definative answer please post!!

[Trent L]

1st port of call is always the one way valve .... it's the easiest to get to & cheapest to replace.

If the issue is actuators, save yourself some grief & do both of them. It would be a shame to rip stuff out & replace the wrong actuator - then have to do it all again, just for being a tight arse.

They can develop literally a pin hole leak over time - but it's enough to cause the demist under acceleration effect.

[CAPRILICIOUS WL]

I had this problem in my previous car a WL Stato and in current car a WL caprice.

It's not so bad in my car atm but would love a fix to it as its really irritating on the freeway every time u put ur foot down. Lol

Iv changed my heater tap and the one way valve on the back of the engine.

I'll be doing the actuators next so hopefully that should fix it.