CCU problem?
07-29-2004, 01:58 AM
#1
4th Gear
Thread Starter
Join Date: Dec 2002
Location: Los Angeles
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
CCU problem?
The problem started with a blown #1 fuse in the trunk (25A) for the AC compartment blowers. Located a bad passenger side blower (with Adrians help) and ordered a new one. While waiting for the new blower, I replaced the fuse and the AC compressor would operate, although at low air volume air only one of the 2 blowers functioning.
Then 2 other problems occured. 1) The oil cooler fan comes on as soon as the ignition is turned on and runs continuously and 2) the AC compressor isn't getting any power although the indicator on the AC button on the CCU is lit.
Have now replaced the blower and it works OK, but haven't had any success with the oil cooler fan and AC compressor. The compressor works if I run 12V directly to it. I also had the freon charge checked and its OK. My mechanic called tonight and said he took the CCU out and it looks as if some component is burned--I'm an EE so I'll pick it up in the morning and take it into work but its tough to troubleshoot circuits without a schematic.
It seems logical that all these things are related and now I'm suspecting the CCU. The local dealer wanted $1210 for a new CCU--a little too expensive just to try out. Can anyone offer advice, schematics, possible place to get a new (used) CCU to try or.... Its really hot in LA right now.
Then 2 other problems occured. 1) The oil cooler fan comes on as soon as the ignition is turned on and runs continuously and 2) the AC compressor isn't getting any power although the indicator on the AC button on the CCU is lit.
Have now replaced the blower and it works OK, but haven't had any success with the oil cooler fan and AC compressor. The compressor works if I run 12V directly to it. I also had the freon charge checked and its OK. My mechanic called tonight and said he took the CCU out and it looks as if some component is burned--I'm an EE so I'll pick it up in the morning and take it into work but its tough to troubleshoot circuits without a schematic.
It seems logical that all these things are related and now I'm suspecting the CCU. The local dealer wanted $1210 for a new CCU--a little too expensive just to try out. Can anyone offer advice, schematics, possible place to get a new (used) CCU to try or.... Its really hot in LA right now.
07-29-2004, 02:12 AM
#2
Three Wheelin'
Henry,
Looking back at previous posts on the subject reveals a place called "Ottos Venice" who will repair the CCU for around $300. They are in California (Venice Beach maybe??) but they have a web site at http://www.ottosvenice.com/ so it might be worth a look.
Best of luck,
Dave
Looking back at previous posts on the subject reveals a place called "Ottos Venice" who will repair the CCU for around $300. They are in California (Venice Beach maybe??) but they have a web site at http://www.ottosvenice.com/ so it might be worth a look.
Best of luck,
Dave
07-29-2004, 02:20 AM
#3
4th Gear
Thread Starter
Join Date: Dec 2002
Location: Los Angeles
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Thanks...I'll try that if I can't repair it myself. Maybe if I drive down there they will have one I can substitute to verify if thats really the problem.
07-29-2004, 10:45 AM
#4
Addict
Rennlist Member
Rennlist Member
Join Date: Jun 2001
Location: Dana Point, CA
Posts: 2,537
Likes: 0
Received 0 Likes
on
0 Posts
Henry,
If you happen to be in South Orange County, you're welcome to try my spare CCU long enough to see if it fixes your problem. The only thing it doesn't do is run the oil cooler fan automatically.
With respect to your compressor, do make sure all of your fuses are good. I just helped someone who's compressor wouldn't engage, his problem turned out to be a fuse he had pulled for the fog lights. Unfortunately, the fuse is shared by the A/C compressor relay control power (and the back-up lights). He reinstalled the fuse, his A/C worked again.
With respect to the oil cooler fan, have you made sure the oil cooler temperature sensor is still connected? Has continuity to the CCU? If the CCU senses an open circuit at the sensor, it runs the oil cooler fan in fast-speed continuously, when the ignition is on.
Hope this helps, and good luck!
If you happen to be in South Orange County, you're welcome to try my spare CCU long enough to see if it fixes your problem. The only thing it doesn't do is run the oil cooler fan automatically.
With respect to your compressor, do make sure all of your fuses are good. I just helped someone who's compressor wouldn't engage, his problem turned out to be a fuse he had pulled for the fog lights. Unfortunately, the fuse is shared by the A/C compressor relay control power (and the back-up lights). He reinstalled the fuse, his A/C worked again.
With respect to the oil cooler fan, have you made sure the oil cooler temperature sensor is still connected? Has continuity to the CCU? If the CCU senses an open circuit at the sensor, it runs the oil cooler fan in fast-speed continuously, when the ignition is on.
Hope this helps, and good luck!
07-29-2004, 05:53 PM
#6
4th Gear
Thread Starter
Join Date: Dec 2002
Location: Los Angeles
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Gentlemen--thank you...I believe I've fixed it. Disassembled the CCU and found a couple of burned traces on the PCB's, one on the top PCB and one on the bottom. I can't tell what they are without a schematic, but I repaired them and that fixed the problem.
Burned out traces are usually an effect not a cause. It's possible (or probable) that I accidently shorted something that burned these traces when I was working on the original AC compartment blower problem. Still--another poor electrical design from Porsche, all the outputs should be protected by fuses.
Burned out traces are usually an effect not a cause. It's possible (or probable) that I accidently shorted something that burned these traces when I was working on the original AC compartment blower problem. Still--another poor electrical design from Porsche, all the outputs should be protected by fuses.