96 C4 AC/Heat Blower/Vent problem

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dsopata@aol.com - 12 Jul 2007 13:05 GMT

My AC/Heat works great but it will not switch from blowing from the
floor vents to blowing out the dash vents, it use to do it aftewr a
few minutes or so but now it has stopped doing it and stay on the
floor vents no matter what switch location i put it on,should I assume
since I am having problems with my Cruise that I have a vacum problem
thats related to the venting system? I have the climate control
option. Any help appreciated.

Dave

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JimH - 12 Jul 2007 17:36 GMT

> My AC/Heat works great but it will not switch from blowing from the
> floor vents to blowing out the dash vents, it use to do it aftewr a
[quoted text clipped - 5 lines]
>
> Dave

I had both symptoms in my '93. The vacuum check valves had gotten
brittle and cracked. It took several times to the dealer to get them
all, but now both dash controls, and cruise control are working well again.

Jim

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Dad - 12 Jul 2007 17:57 GMT

>> My AC/Heat works great but it will not switch from blowing from the
>> floor vents to blowing out the dash vents, it use to do it aftewr a
[quoted text clipped - 14 lines]
>
> Jim

Boy, that sucks ;-))

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Scubabix - 22 Jul 2007 01:31 GMT

>> My AC/Heat works great but it will not switch from blowing from the
>> floor vents to blowing out the dash vents, it use to do it aftewr a
[quoted text clipped - 11 lines]
>
> Jim

Ditto on my 96
Rob

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sifwarrior@gmail.com - 05 Aug 2007 02:33 GMT

> dsop...@aol.com wrote:
> > My AC/Heat works great but it will not switch from blowing from the
[quoted text clipped - 12 lines]
>
> Jim

Same w/ my '93. The culprit was located on the passenger-side under
the "Corvette" engine shield over the manifold. Just follow the vacuum
lines to identify it. Problem with mine was a crack in the neck of a
barb that entered the check proper. I was able to use some silicone to
repair the connection and now everything works fine. Good luck to
anyone with the same problem.

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Dleer - 27 Dec 2007 01:42 GMT

Mine is stuck such that it only blows on the widshield, I have the GM
service manual but it refers you to 95 service manual for details of the
plenum valve that controls this re-direction function. Looks like a tough
problem to find and fix. Let me now if find out how --- i'll do likewise

'96vette

> My AC/Heat works great but it will not switch from blowing from the
> floor vents to blowing out the dash vents, it use to do it aftewr a
[quoted text clipped - 5 lines]
>
> Dave

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bob.kirkpatrick@heapg.com - 28 Dec 2007 17:17 GMT

> '96vette
>
[quoted text clipped - 4 lines]
> > My AC/Heat works great but it will not switch from blowing from the
> > floor vents to blowing out the dash vents, it use to do it aftewr a

Dave,

My '96 started doing exactly the same thing. The dealer thought it
was a computer problem and yours may very well be a vacuum problem but
the fix for mine was simply to refill the Freon and fix a slow leak.
It seems that the AC computer doesn't want to blow warm air in your
face so it waits until the evaporator coil gets cold enough before
turning on the dash vents which normally takes less than a minute. As
you lose Freon this takes longer and longer until the AC can't get the
coil cool enough to convince the computer to enable the dash vents.
It's still cooling and the floor vents feel cool but apparently not
enough. The C5's don't do this so I assume Chevrolet realized it was
a problem.

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