mr_bock

Hi Fellow Rennlist People,

I have been trying to chase down my low A/C cold air performance since a few years ago when I took on the task to replace the Evaporator, Receiver Dryer, and rebuilt the Compressor. After all of that and a recharge by a local shop, the cold air was disappointing to me. I gathered lots of data about how the whole system works including the flapper valves, etc.

From observation, it looked like the defrost flap valve servo was 'stuttering' while activated. I removed the motor, split the case (lots of snap clips) to get to the PCB. After I cleaned the PCB tracks and Contacts with a soft #2 pencil eraser and alcohol (there was some black residue that came off). While working on putting the servo halves back together, several gears fell out. It is not obvious where they go! Does anyone have pictures of this that should make this assembly clear?

I searched high and low on this Forum and the Web....

Any help would be greatly appreciated!!!!!

Big Major Thanks!!!!!!!

Twilightblue28A

Mr. Bock,

Be patient. PP00830, AKA Andy will provide all information, and more, relating to servo motors. You will receive detailed instructions on rebuilding servos, Andy's "toothpick" tip for separating the case, the name and email address of the company that sells replacement parts, and also instructions regarding the length of time to rebuild your servo. Andy will also describe an alternate use for your kitchen table. Look for the yellow submarine. We should rename PP00830 "SERVOMASTER." This information will all come together as soon as Andy responds.
Be patient. You won't be disappointed...

ToreB

Here's a pic. There are two identical gears in the servos, the one on top and the rightmost gear in this pic.
Use grease sparingly, especially on the worm gear, or it will move to slow. Do not use petroleum based grease, it will damage the plastic. If the large output gear (with the rotating contacts) is separated from the axle, it is very important to reassemble in the correct angle.

The most common cause for servo failure is a worn-out motor and resulting short-circuit. This causes excessive current and damages the end-of-travel switch tracks, and sometimes the CCU output drivers too.
The only remedy for this is to replace motor, PCB and output gear with sliding contacts. PARTisan Autoteile in Germany have a refurbish service and sells kits.

Cheers,
Tore

pp000830

Servomaster?
Hi Harry, Thanks for the reference.
Mr Bock, Here are my thoughts on the subject:
https://993servicerepair.blogspot.co...ning-hvac.html
Andy

mr_bock

I just checked my posting and see these replies from around the world!!! ToreB, that is a great pix of the gear stack! I booked marked Servomaster AKA Andy AKA PP00830 web page for reference. You guys are awesome and Rennlist is The Best for information that helps keep these fantastic automobiles On The Road!!!!!!!

I will report back as to how all this goes and hopefully I can rid all the A/C demons...

THANKS!!!!!!!!

JasonAndreas

This can't possibly be a real post from a real person?

mr_bock

The gearbox pix is worth a thousand words... I was able to reassemble my servo and tested it in the car (power only) and it worked as it should. Next I had the shaft coupling engaged with the flapper shaft and that is good.
Great info given.
I will go ahead and open the other servos and clean the PCB traces and whiskers, etc..
I want to insure that all of the internal flaps, controls, etc are working properly before I see about having the A/C system evacuated and recharged.

Hopefully I get nice amount of cold air from the vent(s).

mr_bock

I may have found the problem... I had the CCU partially pulled out of the dash and using a led light to see into the flap valve. When I turned on and off the recirculate button, I could see the flap valve move in a irregular/erratic manner. I pulled the glove box, the radio, ccu farther out and there I saw the mechanical lever arm that was just dangling. Seems that the pivot rod is missing that connects the arm to the flap. I don't know if I missed this when I did the evaporator replacement or it was lost many years ago. I will have to come up with a replacement on my own as this does not show up in the Porsche PET parts list.

Does anyone have suggestions for a replacement? I will investigate this as to rod diameter, length and some sort of retaining clip.

This is a big step in the fix!!! I will still clean the servos and make sure there are no other issues.

To be continued...

Twilightblue28A

Mr Bock,

I will be surprised if another member doesn't provide a solution to solve the pivot rod that you have described. By the way, you did a great job troubleshooting. Stay tuned..........

ToreB

Searching is your best friend on this forum:
https://rennlist.com/forums/993-foru...connected.html

T

mr_bock

ToreB, You are the Man! The pix in the link is exactly what I needed. I am missing the snap button that holds/pivots the arm to the flap door. Now I know what I need to get. Attaching them together in such a limited access area will be 'fun' as I have fat fingers...

Thanks!!!!!!

ToreB

Yes, it can be fiddly to insert the nylon tie, I've done this 3-4 times. If you remove both the CCU and the radio you get better access and can use both hands. It also helps to activate the resirc function on the CCU so the actuator arm is positioned in the outward state.
Cheers,
Tore

mr_bock

Tore,
Thanks for the tip on positioning the arm.

I already had the radio and ccu out last night. Woke up at 5 am this morning and could not get back to sleep so off to the garage I went. In my bag of car bits and pieces, I found some plastic interior mounting clips that use a push pin to expand the clip fingers. Happens to be the right diameter. While test fitting this pin in the upper arm hole that attaches to the door, I find that the lower arm is not attached to the lower door!!!! The little pin and a couple of fiber washers were still attached to the arm. I was able to push the pin off the arm and now see exactly what Porsche used. I will see about getting some push on retainer washers that might be stronger.

The lower arm has even less space to work in... I may have to get my wife with her much smaller hands in there!

With both arms not attached, it is no wonder that I am not getting the cold breeze!!!!

To be continued...

mr_bock

This morning I went looking for plastic pivot pins at Lowe's and at NAPA Automotive. NAPA had a huge assortment of clips and fasteners. I bought several different ones hoping something will work. Here is a pix of what I ended up using. I had both the CCU and radio out of the dash. Using long nose pliers, I was able to get the clip through the holes with a washer in place. Pushing the push pin expands the clip shaft. Now with the engine running, both air flaps that go to the evaporator open and close very smartly as they should.

Tomorrow I will recharge/top off the Freon and test the A/C for hopefully nice cold air. I have a digital multimeter with temperature thermal couple to check center vent readings.

Success, time for a drink!!!!