milutintin

http://www.ebay.de/sch/partisan-auto...&_trksid=p3686

If you click on any of them you will get an english description.

nine9six

Euro to US dollar conversion still puts these refurbished units at $284 US. I dont see this as a cost effective replacement over a new unit from Sunset for $300, or the new Pelican Parts unit at $265...What am I missing here?

pp000830

In the old days of the 930 the rotary blower **** between the seats went to a controller in the engine compartment with lots of components in it and a strange delay timer, involving a glass magnetic reed switch, so the blowers would wait for a warm engine before turning on. The entire set-up was a kluge. I rewired the rotary ***** so the micro-switches on it ran the fan motors directly. A much simpler reliable solution that had little impact on the functionality of the system.
Now that I have a 993 it seems to me a long term reliable solution could probably be worked out along similar lines. HVAC was never Porsche's strong suite on any of their air cooled cars. I bet there is a solution for the fried circuit board. If not I bet a circuit board hobby hit could be used to recreate the board. Whoever does this first has a ready-made market to sell into, like the guy who sells the 5 cent gears to fix to odometer on the 993 for $50. I think the Rennlister guys would pay $100 for a pair of matched boards for each left/right air valve set. Cost would be < $5 each to make them even in low volumes. Any takers?

Andy

IainM

This thread should be a sticky

I think Porsche knows exactly what that module is worth. As an EE it seems to me that the design can handle the stall current of the motor. I think the previous poster was right, the motor commutator shorts out from accumulation of copper dust and burns out PCB (and the whiskers - ask me how I know)
thru direct battery short.
Replacing just the PCB isn't a fix. The shorted motor will burn that out too. The question is, if you blow out all the copper dust, is there still enough meat on the brushes for another 17 years? I suspect not.

Hence $250 for a new module from Porsche is probably best deal especially if you include time.

Livefreeandrive

Hi, I read somewhere on here where someone has done that. Is it just an intake and a 96+ ECU? I know I have the extra connectors in the engine bay?

creaturecat

Aren't they almost 500 bucks each from Pelican?

nine9six

What I have learned is pricing fluctuates based upon availability of parts. Supply high, part price low; supply low, part pricing high.

This seems to be the case for both a distributor (i.e; Pelican) or Porsche.

mgianzero

So what ever happened to this project? Tore, are you still working on a cost-effective solution to repair or replace our servos?

Do these servo units really use servo motors (a motor using true pulse technology) or are they just standard low-voltage motors with some gearing and a potentiometer to read their position?

(Pardon me if I'm not describing myself using the appropriate terminology --- but I'm learning.)

ToreB

mgianzero, you are right, these are simple geared servos with limit switches and a potentiometer for feedback. Partisan Autoteile have a good refurbish service going, (linked in a earlier post in this thread) so I have focused on other things.
Cheers,
Tore

therossinator

So lets see if I've got this correct: it would be smart to take apart working servos to blow out the copper dust to prevent future failures?

ToreB

The servo motor commutator wear, and thus the problem with copper dust. I guess the brushes also has weared out. I have tried to open those small motors, to no avail. They are made of very hard metal, you might be able to open them, and maybe clean out the internals. I would guess it would only be a temporary fix, I'ts very difficult to refurbish such small motors, if possible at all. The PARTisan guys change the motor, as well as the PCB in the servo. That leaves only the gears to be original.
Cheers,
Tore

mgianzero

When I've pulled several of these sevos apart, the motors appear to be "on their way out" or bad. You can literally see the communicators sparking and the motors run hot. When I've changed the motors to an aftermarket one, they've seemed to work fine. I think the weak points lies with an open circuit board, under powered motors and possibly a poor feedback system that does not protect these motors from high torque conditions.

But Tore is certainly more of an expert than me on this. Seems funny, however, that we don't really hear of these problems with the newer (996, 986 and beyond) Porsches. Guess the technology was just not there when our cars were built.

nine9six

Part of it could be due to this being a 993 forum...

Give em time...The oldest of the 993 series is 19 thru 16 yrs old. I'd say the servo's and motor did a fairly good job of survival. But then again, nothing lasts forever.

Any 996/986 owners care to chime into the HVAC servo conversation?

Twood

I have one failed air mixer servo motor, another that is looking old plus a failed foot well servo motor. Add up the cost of having these fixed/replaced is the reason I want to follow this thread.

MDamen

I am replacing my fresh air servo today. It gets exercised each time the car is started and has finally worn out. I opened it up and it was the motor that was bad. It would be nice to have a fix that just replaced the motor.