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Damaged HVAC servos could be history

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Old 10-14-2012, 01:31 AM
  #16  
x50type
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Lorenfb

Are you talking about this motor?

Last edited by x50type; 10-24-2012 at 10:36 AM.
Old 10-14-2012, 01:49 AM
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Lorenfb
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"Are you talking about this motor? "

That's it! All the ones I've been asked to fix have had bad commutators and thus
non-repairable. One needs to open the motor, i.e. very easy to open/close it.
Old 10-14-2012, 10:24 AM
  #18  
IXLR8
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Originally Posted by Lorenfb
All the ones I've been asked to fix have had bad commutators and thus non-repairable.
That sounds like the Valeo starter motor that was said to be non-repairable. At $833 at the time, I repaired it.
Old 10-14-2012, 10:39 AM
  #19  
IXLR8
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Originally Posted by ToreB
That's an Interesting question Alex.
The unloaded motor current is about 80mA, rising to about 430mA at full stall.

Cheers,
Tore
Considering the shape of those whiskers and tracks, I would have expected a higher current. They look burned.

You've stated that they are "resistive" carbon tracks...correct?
Old 10-14-2012, 01:15 PM
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Lorenfb
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"You've stated that they are "resistive" carbon tracks...correct?"

No. They're not resistive. As stated, they're just connections which
limit the travel of the motor.
Old 10-14-2012, 11:20 PM
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This seller on eBay Germany refurbishes these servos:

eBay seller: partisan-autoteile

This is their item listing:

eBay inventory: partisan-autoteile

This is from one of their item descriptions:

"*** English product description ****
Flap actuators servo motor for heating/climatic control Porsche 964. OEM part number 964.624.324.00 96462432400

This servo motors moves the temperature mixing flaps (left/right). This part is two times mounted in all Porsche 964 models.

If the heating in your car is stuck to hot or cold, this part is the most likely cause for this misfunction.

These servo motors are generally overhauled, that means all wear parts are replaced by remanufactured, new components from up-todate automotive production. The sleeve contacts and the new printed circuit board are plated with 3µm hardgold (cobalt-dotted gold). The electrical motor is an OEM part.

By using highest quality materials, maybe the overhauled servos are more reliable than originally! We test every repaired servo before shipping and give a 24 month guarantee.

Delivery is only possible when the broken part is sent to us! Please send your defective servo as soon as possible to us. We ship out the new servo at the same day the old one arrives here.

Please note:
- The shell of the old part needs to be without any cracks. Please do not try to open it, because the plastic case might break. If the servo is not working, it usually is a “total loss” and it can not be easily repaired.
- Please remove the metal bracket before shipping it to us. Do not remove the lever. We will send it back perfectly adjusted."


So, it seems that they have found a source for the OEM motors, perhaps a cheaper or more readily available servo unit from Porsche?
Old 10-15-2012, 03:48 AM
  #22  
Lorenfb
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"This seller on eBay Germany refurbishes these servos:"

Obvious not a simple track fix since the exchange/rebuilt price is 249 Euros,
about $300 each.
Old 10-15-2012, 08:01 AM
  #23  
ToreB
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The company seem to keep the mechanical components only, and changes the PCB, motor and brushes/whiskers. That's a thorough and durable solution, but what a price! As far as I know, this is about 2/3 of the original part price.
Cheers,
Tore
Old 10-15-2012, 02:58 PM
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x50type
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The German refurbished servo at 249 Euros [or $322 today's rate] seems high and packing and mailing 2 way will be extra!.

I got a new one [993.624.325.00] from my local Porsche dealer last November for $209.46 plus $18.33 sales tax.
Old 10-15-2012, 08:55 PM
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I appreciate that the refurbishment is expensive, but my point was simply that the refurbishment is possible - perhaps the eBayer feels he/she can charge what they like because no-one else seems to be offering the service.

It's likely that within the next five years, demand for these motors will rise exponentially as they reach the end of their life span. It'd be nice to know where to send them for a quality rebuild when this happens - perhaps a service that Loren or Tore might offer in the future?
Old 10-16-2012, 04:59 AM
  #26  
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I'm certainly lokking to this now, and maybe will offer a refurb service or something.
We'll see...
Cheers,
Tore
Old 10-16-2012, 10:50 AM
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Originally Posted by ToreB
I'm certainly lokking to this now, and maybe will offer a refurb service or something.

Cheers,
Tore
Tore, I'd sooner just be able to buy the parts. Boards are cheap to have made based on my coworker designing and then sending a file over to the board manufacturer. The gear and whiskers are the other part I would buy.

I'm thinking about stopping by that rebuilder since I am there every summer.
Old 11-01-2012, 04:15 PM
  #28  
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Originally Posted by ToreB
Loren, I've never seen any failing servo motors, but must have seen at least 150 servos with burnt limit switches. To me, that's pointing to what's the most common fault in these servos.
You may have other evidence than me on this?
Cheers,
Tore
Yes, I agree with Loren. As you can see from my post the electric motor went bad and not the circuit board. It would be great to just replace the electric motor. Where can I find a replacement without buying a whole new servo mechanism? As you know, it's the identical motor in all of the servos.

Marc G.
Old 11-05-2012, 07:26 PM
  #29  
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Hi Tore,

1. Was wondering what told the CCU to stop sending current to the pins to turn the motor? If you short the 2 pins mentioned in the first post, the motor pins will always see 37 ohms no matter where the arm is. Shouldn't this produce consistent current feed and wouldn't that rather quickly kill the motor?

2. Also, if the variable resistance units swept outside of their limits and opened the circuit, then no amount of current will ever reach the motor because its an open loop. By default, dead in the water. What may be happening with the tracks is that when a crack happens somewhere, it produces an "open loop" within an acceptable range of motion for the arm, but won't ever respond. So if we could solder over the tracks somehow, we could remedy this? This should fix the feedback loop signal created by the extra 3 pins, right?
Old 11-05-2012, 07:28 PM
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IXLR8: Whiskers should be pretty hardy relatively speaking. Do you have a source to send the circuit board to for replacements? We could be on to something here!!


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