1990 ac vents wont switch
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Joined: Jan 2010
Posts: 90
Likes: 4
From: Henderson Nevada
1990 ac vents wont switch
My 1990 vert with the auto air controler. The temps switch but no matter what position I switch the blower it only blows out the defrost,and floor vents. I searched and found threads on blend doors but my temps switch i just need the air out the front. Any help is appreciated. Thanks
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
I just went through this last week. For me, it turned out to be my check-valve under the hood. The vacuum line goes from the rear plenum into the check then tees off to the HVAC line and the cruise. Thank God it was that, the other option is the programmer board under the dash above the gas pedal, which looks like a PITA.
Burning Brakes
Joined: Apr 2009
Posts: 877
Likes: 0
From: Broken Arrow Oklahoma
if your cruise doesn't work then go to the valve mentioned above. On mine it was the programmer. Be sure you remove the push fastener that holds the vacuum tree to the programmer, the hoses are not long enough to remove the programmer first. Use a small flat blade screwdriver to pry it off.
Burning Brakes
Joined: Sep 1999
Posts: 786
Likes: 31
Cruise-In II Veteran
First: Check for any codes:
http://www.corvetteactioncenter.com/...agnostic+Codes
Second: Clean the controller push button contacts:
http://forums.corvetteforum.com/c4-g...on-repair.html
I'm lazy so I always try the simple things first; then dig into the tougher ones. Those two suggestion may save some work if they indicate or resolve the problem .
http://www.corvetteactioncenter.com/...agnostic+Codes
Second: Clean the controller push button contacts:
http://forums.corvetteforum.com/c4-g...on-repair.html
I'm lazy so I always try the simple things first; then dig into the tougher ones. Those two suggestion may save some work if they indicate or resolve the problem .
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
A bad vacuum check valve can cause this. If your cruise control works then it is OK.
Otherwise, it's probably the HVAC programmer.
As mentioned by RLG, there is a press-on clip buried in the middle of the cluster of vacuum lines on this vacuum line block that needs to be removed (you can "unscrew" it with a sharp probe):
Otherwise, it's probably the HVAC programmer.
As mentioned by RLG, there is a press-on clip buried in the middle of the cluster of vacuum lines on this vacuum line block that needs to be removed (you can "unscrew" it with a sharp probe):
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