CCU Interior Blower/Fan is blowing 25A Fuse
05-15-2013, 11:21 PM
#31
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As I read and continue to learn, I think I have 1 more thing wrong. The rear blower fan does not start up when I get home. I thought it used to and should run for a few minutes to aid cool down after I shut it off. Is that affected by the front blower fans not running and that I have them set to "0"??
05-16-2013, 11:46 PM
#32
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High or low speed is controlled by the CCU using the rear blower relay. The rear fan runs on low speed if powered through the resistor, or on full speed if feeded with 12V.
The resistor reduce the motor current, thus low fan speed. There's no practical way of doing this in the 993 other than using the resistor. It gets very hot, and is therefore mounted inside the air duct for proper cooling.
The CCU has a feedback line from the blower motor, and will switch to high speed if nothing happens when trying low speed. This is a safety feature. If there's no connection when Ohming the two resistor terminals I recommend changing it. It might be possible to reset the thermoswitch by pressing it using a needle, but I have never seen a such a case, only failing thermoswitches. I therefore always change the resistor assembly.
Cheers,
Tore
The resistor reduce the motor current, thus low fan speed. There's no practical way of doing this in the 993 other than using the resistor. It gets very hot, and is therefore mounted inside the air duct for proper cooling.
The CCU has a feedback line from the blower motor, and will switch to high speed if nothing happens when trying low speed. This is a safety feature. If there's no connection when Ohming the two resistor terminals I recommend changing it. It might be possible to reset the thermoswitch by pressing it using a needle, but I have never seen a such a case, only failing thermoswitches. I therefore always change the resistor assembly.
Cheers,
Tore
05-20-2013, 11:40 PM
#34
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Firewall out. Blower removal tomorrow. Should have replacements Wednesday!
This link from Tore was very helpful. http://www.964c2.se/?p=167
Since this is C2 and mine is C4 there were some slight difference. Specifically there were two plugs not on post.
This link from Tore was very helpful. http://www.964c2.se/?p=167
Since this is C2 and mine is C4 there were some slight difference. Specifically there were two plugs not on post.
05-21-2013, 08:11 PM
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Quick question.
Got to the fans. Not out yet. Should I be able to turn them with some ease? They were pretty stiff.
Most electric motors I encounter I can spin, especially this size.
Got to the fans. Not out yet. Should I be able to turn them with some ease? They were pretty stiff.
Most electric motors I encounter I can spin, especially this size.
Last edited by RayB_911; 05-21-2013 at 08:40 PM.
05-24-2013, 01:47 AM
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Went from this....
To this!
Replaced both fans, from PartsHeaven after couple days of extra lube and cleaning armature best I can.
Also replaced resistor on rear blower.
Clear faults, did tests, ran diagnostic scan again, no faults. All fans appear to work.
I was able to free the original blowers and spin them with battery, but,still need work. Plan to keep lubricating and hope they can be spare until I find
place that will rebuild.
THANK YOU for all the advice and direction. I read so many threads with this project that I think I have also learned how to perform better searches for Rennlist.
To this!
Replaced both fans, from PartsHeaven after couple days of extra lube and cleaning armature best I can.
Also replaced resistor on rear blower.
Clear faults, did tests, ran diagnostic scan again, no faults. All fans appear to work.
I was able to free the original blowers and spin them with battery, but,still need work. Plan to keep lubricating and hope they can be spare until I find
place that will rebuild.
THANK YOU for all the advice and direction. I read so many threads with this project that I think I have also learned how to perform better searches for Rennlist.
05-24-2013, 03:43 AM
#37
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Good job Ray, congratulations.
Cheers,
Tore
Cheers,
Tore
05-24-2013, 07:30 AM
#38
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Hi, thanks for all the excellent info. in the post.
One quick question - in my 993 the number 1 fuse is blowing ( the 25amp one ).
I don't have any OBD diagnostic kit.
Is there a way to disconnect the power to each blower motor in turn - to try and work out which one is blowing the 25amp fuse?
( apologies if I have asked a question that is already covered in the post! )
One quick question - in my 993 the number 1 fuse is blowing ( the 25amp one ).
I don't have any OBD diagnostic kit.
Is there a way to disconnect the power to each blower motor in turn - to try and work out which one is blowing the 25amp fuse?
( apologies if I have asked a question that is already covered in the post! )
05-24-2013, 08:41 AM
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Hi, thanks for all the excellent info. in the post.
One quick question - in my 993 the number 1 fuse is blowing ( the 25amp one ).
I don't have any OBD diagnostic kit.
Is there a way to disconnect the power to each blower motor in turn - to try and work out which one is blowing the 25amp fuse?
( apologies if I have asked a question that is already covered in the post! )
One quick question - in my 993 the number 1 fuse is blowing ( the 25amp one ).
I don't have any OBD diagnostic kit.
Is there a way to disconnect the power to each blower motor in turn - to try and work out which one is blowing the 25amp fuse?
( apologies if I have asked a question that is already covered in the post! )
I found posts here that explained how to test the motors by pulling the cable off the blower heat sink and gronding two cables as below.
"I disconnected the connector of the final stage amplifier and applied ground (momentarily) to pin 1 (BR/RE) and pin 6 (BR/GR) on the connector. Had a good arc on both, but no fans moved. nothing but some arcing. SO.... Fans bad or seized, correct?! CCU seems to be functioning"
I got this from thread here, but I have looked at so many and subscribed to them all I don't know which one. Otherwise, I would post link for you.
I also highly recommend getting familiar woth Tore's site in understanding the CCU function, tests etc. http://www.bergvillfx.com/porschehvac2.html
03-29-2016, 07:14 PM
#41
UPDATE
I disconnected the connector of the final stage amplifier and applied ground (momentarily) to pin 1 (BR/RE) and pin 6 (BR/GR) on the connector. Had a good arc on both, but no fans moved. nothing but some arcing. SO.... Fans bad or seized, correct?! CCU seems to be functioning.
I disconnected the connector of the final stage amplifier and applied ground (momentarily) to pin 1 (BR/RE) and pin 6 (BR/GR) on the connector. Had a good arc on both, but no fans moved. nothing but some arcing. SO.... Fans bad or seized, correct?! CCU seems to be functioning.
thanks in advance!
