UKKid35

Which actuator is this? I bought it ages ago but I never got round to fitting it.

shadowknight

the part above is for the defrost flaps... I just put one in today.

ROG100

No need to buy those anymore as I have the replacement diaphragms.

UKKid35

Can you give me rough idea how long the job takes - many thanks

dr bob

Roger-

I have symptoms of vacuum system failure. Comb flap doesn't pull all the way, and the heater valve doesn't go all the way closed.

What have you got for replacement diaphragms so far? I need to go in there with the miti-vac to find the specific failure, but if the console is coming out they all deserve to be fixed if possible. Car is '89 S4. It's black on the outside and so needs the special black-car-only vacuum bits to keep it happy. Can you help me out?

ROG100

A long long story - but so far and a lot of money I only have replacements for the recirc and the defrost.

heinrich

we need servos

heinrich

or better, plain cables

Tails

Roger,

Great news on the diaphragms.

Can you give us a price on the cost of each type of diaphragm?

I noted that there are similar type diaphragms in some actuators and it is only the actuating arms that are different, so more specifically the HVAC has the following vacuum actuators:
A - Fresh air/recirculating flap
C - Defroster flap
D - Footwell flap
E - Bulkhead or Centre flap
H - Heating valve

So can you advise on how many diaphragms and which type are required for a complete change out.

Fortunately A, C, D & E vacuum actuators have removal caps (a bit of a PIA to get off), however, the Heating Valve is fitted with a sealed unit. Are you making a heater valve diaphragm as I have successfully opened up a unit to investigate the reason for failure?

Can the new diaphragms be fitted to the existing actuating arms in situ and if so how are they fitted to the actuating arms?

Look forward to your reply as I need to replace some of mine, as currently only temporarily reparied the diaphragms.

Tails 1990 928S4 Auto

Tails

Nichole,
Well done, it looks surprisingly like mine, as just boxed up my system 2 day ago after a complete inspection, overhaul, repairs as necessary, evaporator clean, bulkhead flap micro switch repair (frozen in the closed positon and repaired by instant technician "WD40"), cabin temperature sensor fan overhauled and sensor resistance check, blower fan removal and cleaned, stepping motor zero adjustment after setting temperature mixing flaps to fully closed.

After all this I note that the metal brace on your car, located just under the centre vent is bent the same as mine was, do you know the reason for this as it is quite strange? Not a substancial brace, so I straightened my in situ as I thought that the PO may have bent it.

Have fun putting it all back together. When I adjusted my setting motor "F" if found that it was easier to adjust by removing the pod, the instrument cluster and the ventialtion tube to the door vent by moving it back out of the way, which also allowed me to get a good view of the defrost flap "C" vacuum controller.

How did you remove the tops from the vacuum actuators? I used 0.020 feeler gauge material with radiused ends which I inserted under three of the lugs and then popped the last one by a small screw driver.

As previously advised you need to stretch the rubber to find the holes which look as though they were caused by the diaphragm being pinched between the internal cylinderical plastic piece (where the spring sits inside) which attaches to the actuating rod and the inside diameter of the actuator body or by the spring as it is compressed.

I did a temporary repair by using "super glue" as the holes were so small. So far working fine.

There is a excellent section in the WSM "section 87" which fully describes the system, how to set it up and the procedure for testing.

Hope all goes well with the reassembly.

Tails 1990 928S4 Auto

shadowknight

To remove and replace the defrost diaphram took me about two hours. The center comb I think is the worst, I must have spent three hours inside the car with a flash light and mirror trying to reattach the conncecting rod to the arm and dropping alot of F bombs along the way, Not something I want to do again in the near future. I did'nt cut a hole which you see in the begining of the post which would have made things much simplier, but rathter used the vent on the passenger side.

auzivision

I see my to do list growing again... ROG100/928sRUS here I come.

ROG100

I have replacements for A & C.
The rest will follow if & if & if - not easy but soon.
As will the plastic insert replacement for the rear hatch receiver.

the flyin' scotsman

Roger............I haven't followed every thread on the subject so perhaps this has been asked before.

Can we not make a mold from the OEM diaphrams and make new with modern synthetics? Anybody out there knowledgeable of rubbers?

ROG100

Malcolm,
My very thoughts of about 9 months ago.
I have disscussed this with a number of molding shops with varying degrees of success.
The issue is the low volume. I am looking at min runs of 10,000 off along with high tooling costs of $5 to 10K.
At that price and commitment I want to own the tooling.
Then there is the issue of copyright. A lot of molding shops are very wary of producing a Porsche part.
I will get there eventually.
Already have the recirc and defrost IN STOCK.
They are the cheaper to repair with new actuators.
The real expensive units are the two console mounted ones and they also fail the most.