Air Flap/Vacuum/Climate Control

Kerry Griffith i2k at
Mon Feb 16 10:29:52 EST 2004

Thanks Brett. I should have mentioned that just to complicate the diagnosis,
current sub-ambient temp for AC operation doesn't involve the boost-induced
flap behavior. I'm wondering if the culprit is the diaphragm "motor" that
operates the flap, since my tech disabled the line that (I think) operated
the door. When that line is reconnected, all flow is diverted to defrost.

As for your rumble flap, are you sure you didn't install a pet door for the
kitty?  ;-)


> From: Brett Dikeman <brett at>
> Date: Mon, 16 Feb 2004 01:19:06 -0500
> To: Kerry Griffith <i2k at>, <200q20v at>
> Subject: Re: Air Flap/Vacuum/Climate Control
> At 4:47 PM -0700 2/15/04, Kerry Griffith wrote:
>> I'm fairly certain that this "fix" was part of an attempt to cure a
>> vacuum-related problem in summer that causes cold a/c air to be diverted to
>> the defroster ducts under boost. My question is: what problem does this
>> blocking of the red vacuum line indicate? Vacuum check valve?
> I'd say you're on the right track with the check valve, if the flaps
> are changing position under boost, unless it's the acceleration
> moving them.  The valve should be between the reservoir(which is the
> blue thing you see hiding in the front fender every time you open
> your door) and the back of the intake manifold.
> An unusual failure, though.  Don't think I've heard of it before.  At
> least the valve should be inexpensive, unless it's part of the
> reservoir.  If that is the case, go to the junkyards, as virtually
> any type 44 donor should fit.
> Door prize to the first lister that can tell me which flap it is that
> makes my car rumble whenever the fan gets going above half-speed...
> B
> -- 
> ----
> "They that give up essential liberty to obtain temporary
> safety deserve neither liberty nor safety." - Ben Franklin

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