[V8] HVAC system output goes to defrost and floor upon acceleration

[Dave Head]

vacuum leak - normally in the vacuum motor that controls the recirc flap 
= hose often falls off, or diaphragm tears...
Failure mode is to switch to defrost.

Scott Simmons wrote:
> I'm pretty sure it has to deal with a drop in manifold vacuum and thus 
> the loss of pressure to vacuum-operated devices.  I think I've had 
> non-Deutsch cars do this too.
> 
> ~Scott S.
> 
> Ed Kellock wrote:
> 
> 
>>I've seen it many times before but I've forgotten the cause and can't
>>seem to find it in the archives.
>>
>>When I open the throttle to accelerate or hold speed going up a hill,
>>the blower output goes to the floor and the windshield.  This is
>>happening on both my Avant and my 93 V8.
>>
>>Is this as simple as a vacuum leak somewhere?
>>
>>On the Avant, I checked the black supply line from the engine and it
>>is still connected in the engine compartment and in the plenum are at
>>the base of the windshield.
>>
>>What else should I look for?
>>
>>Thanks,
>>Ed
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>>
>> 
>>
> 
> 
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