01coccobet

Hi all,
I ask the experts for help
I've a problem these days withmy air conditioning.
Here's the background:
with AC on (small *)and operation at low load (little gas),
AC is regular (right flow and temp).
As soon as I press on the accelerator,I feel the flow of air coming from vents in the dashboard stopping and a hiss or whistle.
Now in the various attempts to search the problem,even with the OBD II, I discovered that the cabin air recirculation is active with:
1 - * small (AC powered)
2 - * large (maximum AC)
3 - recirculation itself.
Now the intermittent operation of the pneumatic valve (vacuum) just behind the AC console commands and the actuator (located in the front compartment above the mixing chamber), had led me to think about a loss of vacuum tubes.
After various attempts I have excluded the vacuum leakage of the hoses and I removed the actuator.

here are the pictures:











The actuator had a pressure cap. (pic 1 bottom left of the actuator)
I removed the cap and found a steel nozzle protected by a spongie thing (photo 2)
Who knows what role has the nozzle with the protective foam?
What are its weaknesses?
how can I test its effectiveness?
How should it work?
blowing or sucking into the nozzle made the air escape only from the upper needle, but I think the bottom needle will work only with the consent of the electric CCU, which was not connected at the moment of the blowing test.

thanks

911PERVY

Have you checked the pipes under the dash are connected to the vacuum unit? Thin white nylon pipe about 5mm goes into a black rubber elbow piece about 10mm. Mine wouldnt go on recirc due to a radio fitter knocking off the thin pipe when installing a new stereo

01coccobet

unluckly it wasn't...
even because the recircul. valve works fine until I step on the gas pedal
so,as Tore states,I should have a vacuum leakage,but not so big...
how can I check it?
my finger is pointing to the actuator 993.605.123.01(or .00 as mine)
that could have some issue.
First I wanted to discover how it works.
Any clue?!?

01coccobet

I just did the tests with the ccu extracted,but connected
I would like make a video of the thing, but I have to drive a car so…,
when you gently rev stationary, the valve is operating normally.
is under load (ie, when I step a little on the pedal) that the valve closes / opens.
At this point I think the main suspect is due to the lack vacuum:
1 - the vacuum lung(plastic big bubble container that serves as a vacuum reservoir placed in the engine compartment near the varioram, which may be lose or badly connected
2-pipe from actuator to vacuum plumb lose
3-pipe from the valve actuator recirc that is leaky
4-actuator which, for reasons unknown to me, once with the engine under load, wear off or even stop the flow (though I think is unlikely).
5-membrane of the valve that is valve (because of a crack), but not too much ( with high vacuum is able to remain open)

Today will do some static tests on the pipelines, I will put them under pressure and try to see / hear if they lose
then at the first meeting with some other Porsche Manic,I'll try with the another actuator.
if this does not lead feedback, I will try to reach the lung, even if what requires the dismantling of the varioram
if then it is too complicated or did not lead to results ....
I'll take the way Porsche dealer .....
I don't give up for sure.
Anyone have an idea of how the actuator works?
Is the nozzle a possible mechanical atmospheric pressure adjuster?
continues .....

01coccobet

this is the misbehaving valve
PS the last pic is property of a RL
thanks

ToreB

I've seen leaks in actuators in the engine, not in the resirculation actuator itself. I've seen one case of bad vacuum line from engine to front, the plastic tube is wrapped along with the electric wire loom, and a short circuit had melted the pipe somewhere along. A pressure test or in fact sucking can determine a leak.
Vacuum leaks can be hard to find, I suspect you have a fault in one of the actuators in the engine bay, they are more subjected to heat than the resirc. The internal rubber diaphragm could then tear due to wear and heat. Here, also connecting a rubber tube and sucking on it would determine the faulty one. You have a couple more than me due to the varioram assembly.
My website have some pictures of such a fault.
Cheers,
Tore

osugasman

How did you remove the recirc unit? Through the front boot?

01coccobet

osugasman
yes taking out the ccu and thru the hole….

I'm almost getting there

accumulator holds,
the feed tube front to back holds,
I have the valve removed and resettled with grease on the seal to help the tight, holds (pain in the *** to work on)
the actuator, works according to P parameters

I went to the dealer to order few things like:
1- a new key (by pressing the alarm button few times due to the immobilizer kicking-in in few minutes while working and needing to light the engine on to check things,the plastic button had enough)
2- a pneumatic valve (in the various research I found a hot air pneumatic valve that did not work .... who's going to ever use the heater?!?)
3- an electrical wire protection (located in the front compartment that was chipped when I changed the battery few months ago)
4- 2 clips of the roof (with the AC out of order,the roof was good thing to use .... then I have devoted special attention to it and I found 2 poor clips cracked)
5- the plastic cover over the big FAN that had little tiny cracks … new as well
6- 2 engine belts (often opening the engine compartment this days I saw them there, always in place and made me tenderly, I told myself that they are always under stress, why not relief them with a possible substitutes in case of ....) (among other things,I ask for help in the do-it-yourself .... can you change them on the street? I saw your suggested list of tools,but is anyone so good to take a picture of the complete set?I cannot figure-out some of them.
I also took away a good chunk of skin of my middle finger while trying to close the recirculation valve with its spring .... among other things while I was working had also disconnected the 2 joints
clip button (not on purpouse) .... I became crazy on how to reconnect them due to lack of space
At the dealer I have done all the tests with a device that measures the tightness of vacuum(I have to get one,sooooo useful)
ok
in short, I came home with a nice shopping bag, but also with a nice re-evaluattion of my local dealer…. today I worked side by side with the boys, and reasoning whit them,getting my hands dirty (mean very dirty) .... shortly,a beautiful day

Final: the offending seems to be a non-return valve on the line

I'll work on it tomorrow ....

…..Continues ..... .....

01coccobet

finally…..

it was the 1way valve between the VR vacuum feed and the vacuum line distributor

here is a pic,in the specific,the bottom-one that you see thru the hole

ciao

osugasman

I also need the "highly prone to failure after 16 years" mixer valve motor--passenger's side. While troubleshooting it, I noticed that the ?pin? that connects the vacuum motor to the articulating arm on the recirculation intake structure had "disappeared". Pump fully functional. Fixed it by convincing a zip tie to crawl in there and offer up his one and only shot at fame by being utilized in a Porsche. Now fully functional. While awaiting the mixer motor, I simply closed the flap valve (tested it with heater on high--no movement towards opening) and have deliciously cold a/c just in time for the >100 degree Cincinnati weather this week.

01coccobet

it seems a common issue...

good shot for you!!

01coccobet

just to update you.
Finally my ac works fine!
the porsche dealer changed a vacuum actuator in the blower(but this shoulden't have much to do with my issue)and disconnected re-connected all the tubes(hoses) of the vacuum line and by my request,hammered the non returning valve....
so the issue is solved,but mistery is in the air.....
hope will help for the future.
ciao

Giuscripa

My car was exactly like yours from 2 years and today I solved the problem: the vacuum lines in the engine were connected wrong. Two of them was changed. The vacuum lines begin in the back of the throtle body. In one of them there is a round valve (one way valve). The vacuum line that goes to the front of the car with the wires from the engine, located on the left side of the engine, should come from the line that has the one way valve. Otherwise, when you step, the vacuum desapears and the recirculate air flap closes, giving you no air. My car also had a fuel pressure problem. Around 4.000 rpms it was heading (not enought fuel). That was because the vaccum line that connects in the fuel pressure regulator instead of beeing connected directely in the back of the throtle body, was connected in the line thas has the one way valve. I changed them (cabin x fuel pressure regulator) and both problems were solved.

morsini

DO you have any pictures of the vac lines you discussed? My tt AC shuts off when I step on the gas and I'm wondering if its the same problem. Thanks.

Michael

01coccobet

Morsini :"are talking to me?!?"
just kidding
if you refer to my issue,the actuar is the one that you se behind the blower,
so as soon as you open the trunk,you'll see it on the left corner just on the left of the BIG cooling fan.
if you need better info(ie a picture),let me know
cheers