WhiteOxmead

Hi there,

I have just finished changing the CCU fan on my 1995 C4 993 RHD, following RicardD's excellent thread on how to perform a fan-ectomy - many thanks.

So just as I was about to push the repaired CCU unit back into the dash I noticed something very strange. Directly behind where the CCU fits way back inside the dash - there is some sort of actuator and a lever which are close to each other...but now disconnected (pictures attached).

Does anyone have any idea what the heck this thing is, what it does, and how to re-connect it ?

The pics are taken from through the hole left by the CCU, its a RHD UK car so the steering wheel is to the right looking at the pics.

All help greatly received.

W



Thanks
WhiteOxmead

badabing

https://www.bergvillfx.com/porschehvac2

pp000830

That is the vacuum actuator that is actuated when you press the recirculated air button on the CCU. It plunger seems to come loose all the time from where it mounts to the vent louver it actuates. I reattached mine to the louver with a tie-wrap other have used a machine screw with a nylon lock nut to replace the lost pin. The picture you provide looks a little different from what is in my car in that the black plastic lever "L" shaped arm seems to be missing on your car as well as the part that attaches it to the louver. The below picture shows the actuator also detached but with the black plastic lever it attaches to in place.
Andy

bjornebo

Perhaps it will be possible to find the black arm and metal levers that attach to the louver. However, per the 993 Catalog, the vacuum actuator, levers, and louver come as a "flap" assembly - PN 993 572 078 00. Available here in the US at Pelican for $198.00.

ToreB

Early 993 models (1994 and possibly the 1995/1 series) have the 964-type spring loaded resirculation flap, and does not use the vacuum actuator.
I have seen this in other cars, and guess the introduction of the vacuum operated flap was gradually implemented in the production process, and they fitted the actuator but just left it unconnected. I expect you have no vacuum hose connected to the actuator, as well as no electric vacuum valve under the windscreen in the luggage compartment.
The Climate Control Unit on these models does not have an output for this actuator, and it is therefore not possible to take into use without upgrading/changing the CCU.
Cheers,
Tore

pp000830

Very interesting, I guess if the original poster's car is a 1995 or earlier model and follows the vacuum hose attached to the actuator and it leads nowhere you are probably onto something.
The only other reasons I can see why parts are missing is part failure or the car was modified for racing in its history and maybe had it removed as part of removing the HVAC system that was later reinstalled but that would be a bit of a stretch in logic.
Andy

WhiteOxmead

Interesting, and kind of wierd.

I took a look under the dash and cannot see either the black 'L' arm nor the parts that would have attached to the vent flap. On close inspection of the actuator and the flap - where the attachment should have been it shows no sight of any use or markings.
I'm sure you guys have hit it on the head - my car's an early 1995 non-varioram and has the basket handle 3rd stop lights - quite an early car, I guess you just didn't get recirculated air in 1995 (Vorsprung dursh technic - as they say...)

The interesting thing is the CCU does have the button, and they bothered to actually fit the actuator, I guess the flap just stays in that closed position - permanently allowing fresh air in for 23 years. I wander how the 964-type spring loaded recirculation flap worked ?

When I get the CCU connected - before I push it back in I will see what it does with the engine on idle (max vacuum) and the recirculation button pressed...

Many thanks for all your help understanding what going on in 24hrs

BR / Whiteoxmead

ToreB

The resirculation function is there indeed. The flap is spring loaded, just as in the 964. If you press the resirc button, the CCU will close the fresh air intake, causing a slight vaccum that draw the flaps open.
This also happens when you have the A/C on, and the temperature setting much lower than the measured cabin temperature. The CCU then will draw/resirculate the cabin air through the evaporator in order to obtain the desired temp as soon as possible.
In the 993, they improved this by having a more controllable actuation of the resirculation flap.
Cheers,
Tore

OverBoosted28

Pdyson4

I have the 964 style sprung actuator but I have the vacuum control valve (under windscreen) and the vacuum hose all the way to the actuator (disconnected and plugged of course) which is weird. Makes me wonder if I can upgrade the actuator to a vacuum type.

I'm also missing the black plastic right-angled and two metal connector parts - no longer available. Has anyone got rough dimensions for these?

ToreB

Only the 1995/2 and later models have the necessary parts for the vaccum-operated resirc opening.
-Does your car have the electric vacuum valve present? It is placed under the plastic cover in the frunk along with the HVAC servo's.
-Part number on your CCU? Only the 993 659 04x 01 units have the vacuum valve control output.

Cheers,
Tore

bobbyp

Tore - when is your web shop re-opening?

Here is my recirc flap:
9/94 built 1995 US model 993

IainM

wow, putting that ty-wrap in ranks in the top 10 fiddliest jobs ever.
My fingers are so sore.