Center vent is weak
Thread Starter
Instructor
Joined: Dec 2003
Posts: 110
Likes: 0
From: Georgia, west of ATL
Center vent is weak
My center vent has almost no air flow. It appears to be redirected to the defrost vents. All of my servos appear to be funtioning properly, so I'm trying to figure out where to go next. Am I going to have to take out the whole unit up front to physically check the flaps that the center servo is attached to? I searched and couldn't find any references to this issue that didn't appear to be servo related.
Thanks in advance for the help,
Jason
Thanks in advance for the help,
Jason
IHI KING!
Rennlist Member
Rennlist Member
Joined: Aug 2001
Posts: 13,400
Likes: 229
From: Nashua, New Hampshire, USA
Jason,
I have a couple ideas to check. When you open and close the manual vent openings, do you hear it move? My car makes a "whoomp" noise when I move the thumb wheel. Also, if you shine a flashlight down into the center vent, can you see the vent shutters open and close? When they are open, is there anything blocking the ducting?
As for the servos, have you checked all 5 servos that they are moving properly? John's 964 web has a good diagnostic procedure for it. http://www.porsche964.co.uk/technical/servos.htm
I have a couple ideas to check. When you open and close the manual vent openings, do you hear it move? My car makes a "whoomp" noise when I move the thumb wheel. Also, if you shine a flashlight down into the center vent, can you see the vent shutters open and close? When they are open, is there anything blocking the ducting?
As for the servos, have you checked all 5 servos that they are moving properly? John's 964 web has a good diagnostic procedure for it. http://www.porsche964.co.uk/technical/servos.htm
Race Car
Joined: Nov 2001
Posts: 4,140
Likes: 1
From: Surrey, UK
I had a problem years ago with the air flow from the vents - it was pathetic. It turned out to be because one of my front fans wasn't running (in my case, the RHS one behind the fuse box).
I never really found the cause - I dismantled some bits and put it back together and it magically worked. My guess would be that your front fans are not running properly (or at least one of them isn't) - if you're sure your servos are OK.
I never really found the cause - I dismantled some bits and put it back together and it magically worked. My guess would be that your front fans are not running properly (or at least one of them isn't) - if you're sure your servos are OK.
Pro
Joined: Jan 2005
Posts: 701
Likes: 6
From: St. Albert, Alberta, Canada
Ditto DaveK's suggestion. I've had it happen two times - first the left hand (driver side) fan seized outright. The right hand fan starting making terrible screeching noises last fall and finally seized up this spring. Those little brass bushings on the motor support just aren't designed to last. A shame that a $0.05 part failure forces you to buy a new $500 motor assembly. (Someone at the Bosch or Porsche finance dept is laughing at us...)
One thing I did that temporarily increased the air flow was to remove the failed motor and tape off the opening into the central chamber. This turned the system into a single blower design and worked well enough to defrost windows and keep you moderately warm on cool days.
One thing I did that temporarily increased the air flow was to remove the failed motor and tape off the opening into the central chamber. This turned the system into a single blower design and worked well enough to defrost windows and keep you moderately warm on cool days.
