Kahdmus

I'll try to remember that!

I guess the 'syndrome; is definitely alive and well! My DIY has all gone horribly wrong this month:

I waited 3 days for a part for my mercedes ml (new MAF) and UPS didn't arrive until after 7pm so Installed in the dark to have the car ready for tomorrow morning...didn't fix the problem that I had been sure it was responsible for and no fault codes. Back to square one on that one!

I guess having another shot at the 964 heater servo tomorrow will give me something to do while I scratch my head over the mercedes...

Blu RS

"have you put 12vdc to #4 and 5 of the assembled servo to test the complete servo?"

Nope, because it's not clear which are the #4 and 5 pins to test, so any photo clarification would be helpful. I've gone over the Baldwin DIY article which makes reference to those pins but in fact it's not at all clear on the pin testing routine, particular with a "buttoned up" unit.

I wouldn't mind testing the servo driver output to confirm whether CCU chip is bad or not, but I think that's unlikely as the right side air servo works fine. My thinking is that the servo driver output is sending the same signal to both driver and passenger side simultaneously so if the passenger side is working then the CCU chip is operating correctly. I'm sure there's a technique with a continuity tester to see whether power is coming thru the cable connector but I'm a complete rookie at electrical testing and don't know the right technique for doing such a test.

I also wonder why someone hasn't scared up the matching VW part number for these servos? There's no way this component is unique to Porsche and there's no way that VW folks are going to pay that much money for a replacement servo.

mojorizing

On the servo, look into the receptacle where the plug pushes in, next to each pin are the corresponding numbers. Polarity doesn't matter - it'll go either direction depending on what's +/-.

The left and right mixing servos use 3 of the four driver IC's. Each IC is half of the circuit for a servo. IC 11 (as marked on the pcb) has one side of the right servo, and one side of the left servo. IC 10 is one side of the fresh air servo, and the other half is the other side of the right servo. IC 12 is the other side of the left servo, and one half of the footflap servo. In other words, half of one driver IC could go bad yet the other servo will still operate.

Blu RS

Many thanks to mojorizing for pointing out the obscure but patently obvious (if you know where to look) numbers for the pin numbers 4 and 5. OK, did the 12V test with jumper cables and paper clips as the terminals and confirmed the module is DEAD, despite my earlier tweaks. So, no doubt a replacement module is called for since I'm at the known end of my talents in this field.

Kahdmus

I just got finished doing mine a SECOND time (I'll KNOCK on wood this time instead of merely 'touching' it as we do on the other side of the pond. When in Rome...right?)

Its all working great and hot air on my side again....yeahay!

I am however guessing that I will need to replace it completely pretty shortly. Out of those part #'s listed by dfinnegan, which is the actual servo?

Also, is there a foolproof way to balance the screws and washers when reinstalling? The only difficult part of the entire exercise is stopping the screws falling down into the never, never! I manage to retrieve the second screw 3 times with a magnet tonight but next time I may not be so lucky.

dfinnegan

Congrats on getting it working again.

They are all the actual servos!

There are 5 of them. The left and right temperature mixing servos have the same part number; and inexplicably have the word "center" in the PET description.

The others are as described in the descriptions and can be cross referenced to the linked pages on the diy.

Kahdmus

Wait..so the big daddy ones are the same and to replace my drivers side it would be:

$291.50 813-05 #10 (2) 964.624.324.00 electric motor temperature mixing flap center (one each side)?

Dang...$300 is a bit silly for such a simple part isn't it?

Thanks for posting these!

dfinnegan

Yup. A bit silly.

For what it's worth, I had the driver's side server failed when I first bought my car. I tried to repair it, but to no avail. I ended up purchasing a used one from one of the breakers (parts heaven, I believe) for something like $50. It's acted up once or twice this year, but seems to be holding up (knock wood!!)

$15/year seems a worth while investment when compared to $300. Of course, there is the time to replace, but that is pretty simple, really.

Cheers

easttorks964cab

hey guys,

i have a problem with my cabin heaters in the fact that the blower speed control *** makes no difference to the strength of the fans no-matter what position it is in. i get cold/hot no problem. any ideas?

stevebozzy

mine did the same, so i disconnected the lever from the servo
then pulled the connecting rod fully out ( gaiter extended)and put the lever back on in the open position.
it only takes 5 mins ,now its permanently warm ! if i dont find a S/H servo before next summer,i will move it back to the cold position.
steve