rkass

Thanks to Brian for helping me out how to fix my problem. After reading above, I performed the following which may be useful to those with just air circulation issues (not a/c or temp control). I am handy but not technical so forgive my inability to put this in precise terms.

Under hood, almost next to windshield is a plastic trim piece that snaps onto back of firewall. It has a 1/2 inch rubber gasket in front that slides onto metal edge of firewall. By lifting up on it it easily comes off. It now exposes certain things, most importantly to me the three servo motors that help with the air circulation.

Looking at windshield, the motor on right (all of these "motors" are small black plastic enclosed things that operate a valve of some sort dependent on the motor.) controls the lower sliding control on your hvac system. You will see to the right of the motor a control arm attached to it that kind of looks like the control arm attached to your inner door handle.

The motor on the left operates the top sliding control on your hvac system ( I may have the left and right motor mixed up re thetop or bottom sliders, but you can determine which is correct) and you should see a white plastic piece attached to the back of the motor. If the servo is working, that white plastic piece goes forward and backwards vs left to right like the motor on the right. The vacuum tube Brian refers to is also attached to this motor and is a relatively thin white color tubing that connects to a black nipple. With the car running, disconnecting the white tubing and placing your thumb over the black nipple should let you know whether you feel a slight vacuum like putting your hand over a vacuum cleaner nozzle but obviously much weaker. Thankfully I did not have any vacuum issues. Brian also mentions that there is an elbow connection inside the car - I found it by looking up in the driver side area and you should see a white tubing similar to the one attached to the servo motor, and this connects via a black elbow tube with the tubing presumably going to the servo.

The third motor in the middle is my problem. By looking at it, it looks like its just a self contained motor. The sliding mechanism is UNDER the motor, so unless you unscrew the two screws holding it in you wouldn't know this. It is held in place because the bottom of the motor is attached to a lever mechanism which is attached to the fresh air flap control. My servo motor is dead. I tested power to the plug by inserting grounded tester into the hole that had the red/white wire. We then unattached motor from lever, put power to the red/white hole and tried to get the motor to operate (for those like me, pretty simple- use battery or charger and connect red alligator clip to positive post and other end to proper power connection in plug; then touch the grounded black connector to the other holes to see if you can get motor to work. If motor is good, this will cause something to whirr around). So my servo motor is bad.

Not all bad news, because it is relatively simple to tape cardboard or something stiff which will "push" the fresh air flap into an open position by artificially pushing in the air flap lever as if the motor was attached and doing this for you.

So there it is. If useful good, if not well took me away from work for 20 minutes.

These things are ridiculously expensive. Does any one have this motor for sale from a race project etc? If so pm me. Tx again to all who helped me solve my problem. Randy

brucec59

Thanks for the follow-up, Randy. I always try to post a follow-up to my, so far, small projects, for the sake of future searchers. I'm having a similar problem with my fresh-air motor thing. The cheapest I've found is from http://www.sunsetimports.com, part 964 624 901 00 for $143.45. It's interesting to know you can force the flap open - I may just do that for the interim, so I can at least get some fresh air. Then again, I like driving with the windows down...

rkass

Bruce, when you take the screws off the motor, gently lift and detach the lever from the bottom. Lift out the motor and you should be staring at what looks like a black stick shift in miniature form, but instead of being horizontal, its vertical. By pushing this rod towards the passenger compartment, your fresh air flap should open up. I think all i did to keep it in this position was to tape a piece of cardboard so this rod can rest against it in the pushed in position. Tx for pricing, that is at least half from my stealer. Not sure if this motor does anything else, but will probably get it for the sake of keeping everything working.

BS911

Great news. At least it isn't a ccu. I'll add your information to mine and send an update to Robin so it will have more info on p-car. (Credits to you of course. )

Another interesting thing I found when trying to brute force my servo back to life. If you pull the thing open you'll find a round board with the contacts that help tell it when to operate and when to stop. I bet you'll find that it has "burnt out" on the board right where the little spring contacts are resting. If you manually turn this gizmo and put it back together with the contacts not on the burnt spot - it will work. That is, until it goes back to the burnt spot. What I haven't been able to find out is how to repair that one little component when burnt through. There was a write up from someone on the 964 side talking about this gizmo in more detail...

http://www.porsche964.co.uk/technical/servos.htm

Who knows, you might be able to have luck reviving yours permanently.

I'm glad I'm not alone in the "forced fresh air" camp. Mine has a combination tie wrap set up to hold the rod in the fresh air position - but it slipped so now I'm forced closed. Ah... a project for the weekend.

Thanks for the update!

Zingari

I have an issue with this servo - except mine is working but the rod that connects to the arm is not opening/closing the flap. Hence I am getting permanent air coming out of the foot vents regardless of CCU air direction settings.

The foot vent control (lower) slider is working fine as I can see the arm/rod moving and I know it goes into the car via the fresh air intake but where is the actual flap the rod connects to and is it accessible?

If anyone has a diagram I would really appreciate it as having spent £££ getting my AC fixed I don't want to dry round wearing yeti boots in summer as my feet freeze.