Air Vents or Ducts PROBLEM!
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Melting Slicks
Joined: Sep 2003
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Air Vents or Ducts PROBLEM!
I have a question?... I went to turn on my AC the other day first time in for ever.... the air would not come out of the dash vents at all, it would only come out of the defrost vents,,,, does anyone know why?
It is like it is not disengaging the defrost!!!!!!!!!!!
It is like it is not disengaging the defrost!!!!!!!!!!!
Race Director
Joined: Mar 1999
Posts: 12,597
Likes: 237
From: Bartlett Illinois
Re: Air Vents or Ducts PROBLEM! (1990CORVETTE)
do you have the Electronic AC controls? with the LCD Display? or the slider for the Temp?
If it is the Electronic AC, I am guessing the Programmer is bad
If it is the Electronic AC, I am guessing the Programmer is bad
Le Mans Master
Joined: Sep 2002
Posts: 8,991
Likes: 2
From: Hanger 18 Taxachusetts
Re: Air Vents or Ducts PROBLEM! (1990CORVETTE)
I bet if you try your cruise control you will find it doesn't work either !!
At least that is what mine did, no cruise and fans only blew out defrost & floor vents.
Turned out to be a vacum T/check valve that had deteriorated. Took what was left of it to the dealer parts counter and without saying a word the guy walked away. He came back a few moments later with the new one. He said it is a common GM problem as this part is used on all GM cars/trucks with AC & cruise.
Mine was located under the fuel rail cover on the passanger side of the engine going directly into the manifold.
$6 part, worth a look.
At least that is what mine did, no cruise and fans only blew out defrost & floor vents.
Turned out to be a vacum T/check valve that had deteriorated. Took what was left of it to the dealer parts counter and without saying a word the guy walked away. He came back a few moments later with the new one. He said it is a common GM problem as this part is used on all GM cars/trucks with AC & cruise.
Mine was located under the fuel rail cover on the passanger side of the engine going directly into the manifold.
$6 part, worth a look.
Racer
Joined: Jun 2002
Posts: 428
Likes: 0
From: Dallas Tx
Re: Air Vents or Ducts PROBLEM! (corvette-pilot)
I agree. I've had both go bad.
Try the check valve first. If the air only comes out the defroster vent (that's the default for no vacuum), then the check valve is a likely suspect.
If the air flow gets random, changing suddenly from the AC vents to off, to the defroster, etc., then the programmer is bad.
Try the check valve first. If the air only comes out the defroster vent (that's the default for no vacuum), then the check valve is a likely suspect.
If the air flow gets random, changing suddenly from the AC vents to off, to the defroster, etc., then the programmer is bad.
Advanced
Joined: Nov 2003
Posts: 81
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From: Columbus OH
Re: Air Vents or Ducts PROBLEM! (1990CORVETTE)
The programmer is in the dash behind the steering wheel just had mine done...not easy. If you don't have automatic controls I have a spare programmer(bought the wrong one first)
Burning Brakes
Joined: Feb 2000
Posts: 824
Likes: 2
From: Camden SC
Re: Air Vents or Ducts PROBLEM! (ples454)
Most vent/AC systems default to the defrost position with no signal. Driver safety thing. As noted above, start checking and make sure there are no vacuum signal problems, bad lines, etc. The shop manual is a big help. The 90 has a very large heating and vent section.
Let us know.
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