Oldsilverback

My 1986.5 is having a problem with the heater control valve and the cruise control. I know both are associated with the vacuum lines and possible leaks. The bladder within the actuator housing is worn. Is there a replacement for just the bladder or do I need to replace the entire housing unit? I looked on 928 International and couldn't find any parts. I'm guessing that I will need to replace the housing and maybe few solenoids- I don't need to remove the entire dash but just under the steering wheel and console- is that correct?

fiatrn

There are several actuators in the heating system. You'll need to test to figure out which are leaking, then replace those. There are several writeups on Rennlist.

Some of the actuators, you can buy just the rubber "bladder", for others you get the whole thing. The Dwayne's garage (sp?) writeup covers everything. Roger sells the parts, and I'm sure the other vendors do if you call them.

Jason89s4

Oldsilverback, I'd would start at the four-way vacuum connection near the brake booster, because you have both the cruise control and the A/C system coming in there, and there can be a "domino" effect from one bad system to the next. I don't really need to say anymore, because there is an awesome article with pictures by John Pirtle. Here is the link:
https://members.rennlist.com/pirtle/svc_act.html

No offense Fiatrn, but reference to "Dwayne's garage write up" doesn't really help out newbies (like me) to the forum! (Until you fart around for a while, you won't know what "Dwayne's garage" is!)
I believe this is what you are referencing:
http://dwaynesgarage.norcal928.org/1...0Procedure.htm
And reference to Roger is: www.928srus.com

Thanks,
Jason

Mrmerlin

Google this
Wallys Porsche 928 HVAC system.

it will give a primer on how the HVAC system works and how to test it

Christopher Zach

Grab a mitey-vac with gauge and start checking things. First start with the vaccum tank line (takes awhile to pump down) then the CC servo line, and also the one way valve (very important, this tanked my cruise control, 5 buck part). Then check each servo to see if it holds vacuum and moves (don't go below -20 bar pressure). If you find one is bad you can always put a vacuum cap on that line off the vacuum valves while you debate if it's worth taking half the car apart to replace... :-)

C

Oldsilverback

Thanks for the comments and suggestions. I replaced all four bladders. Heat is working perfectly (hope that doesn't jinx it) but the cruise engages then starts to accelerate. It disengages no problem. I'm guessing the "brain" is shot in the cruise and will need to be replaced. Any suggestions before replacing it? Anyone have the same experience.

Christopher Zach

Most likely the output FET that drives the servo is shorted. Fairly common failure, there are people who rebuild the controllers and can fix that.

Oldsilverback

Saw your ride was Prussiona Blue- in my opinion the best color for the 928s