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Topic: Cannot change air flow location

in Forum: C3 Cooling and Heating Systems


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Cannot change air flow location (1/8)
 2/16/16 8:56pm
EDT
Former Member

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Wantagh, NY - USA

Vette(s):
1981 Corvette White/Black Interior


Joined: 1/17/2016
Posts: 16

Can someone please advise me on what to check. I cannot change where the air flows from. it just comes out the floor. cannot put in on the defrost vents or the dash vents. Don't know what to look for.
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Re: Cannot change air flow location (2/8)
 2/17/16 9:01am
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20128

You have a vacuum leak somewhere. It's possible the Climate Control control valve in the console has dried out, and is leaking vacuum from there, but the leak could be in any of the vacuum lines for the HVAC system.You'll need to remove the center console covers to get at the control switch....that's where I would start looking.
I think someone here posted a HVAC system vacuum diagram for the later cars...might be worth a search to see.

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Joel Adams
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Re: Cannot change air flow location (3/8)
 2/17/16 10:03am
Sarge81Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.


Joined: 12/3/2001
Posts: 2379

I agree with Joel. During the annual Gathering last year we had a seminars and Q & A at Bair's Corvettes. The HVAC control switch in the center console is usually the culprit. 

I had the same issue with my '81. I decided to replace all my vacuum lines and use a hand vacuum pump to test all the vacuum actuators that open and close the blend doors. It turned out the the problem was indeed the control switch in the center console. 

Cheap fix, but kind of a pain to get to. Anytime I have to access the center console I just yank the seats out of the way. Removing those carpeted side panels are a pain with the seats in. 

Here is a pic from Bair's website on that Heater/AC Vacuum Control switch Part #IN485 Click on this link> http://www.bairs.com/page216.asp


______________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




Click here to see more pics of my Vette on CarDomain.


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Re: Cannot change air flow location (4/8)
 2/17/16 8:40pm
EDT
Former Member

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Wantagh, NY - USA

Vette(s):
1981 Corvette White/Black Interior


Joined: 1/17/2016
Posts: 16

I replaced the HVAC unit. Still cannot switch air vent locations. Any other advice. Does anyone have a vacuum diagram for the system?
Re: Cannot change air flow location (5/8)
 2/17/16 11:23pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 20128

Ed...I have the diagram for an '82 I am sending you right now. I'll dig a little deeper into my archives and see if I can find one for an '81. Don't know if the two years used the same system, vacuum-wise, or not. Thumbs Up

Found it...sent it to you also. Tongue


|UPDATED|2/17/2016 8:23:23 PM (AZT)|/UPDATED|


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Joel Adams
C3VR Lifetime Member #56    

My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: Cannot change air flow location (6/8)
 2/17/16 11:26pm
Sarge81Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.


Joined: 12/3/2001
Posts: 2379

'81-'82's are the same Joel. Thumbs Up
I was looking for my diagram but you beat me to it.

Also read this and check that fitting/nipple  Click >http://www.docrebuild.com/dr-r-web/tip3.html



|UPDATED|2/17/2016 8:26:26 PM (AZT)|/UPDATED|


______________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




Click here to see more pics of my Vette on CarDomain.


Lifetime Member #26
Re: Cannot change air flow location (7/8)
 7/17/16 5:24pm
jim in oregon
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Milwaukie, OR - USA

Vette(s):
'78 Silver Anniversary T Top coupe,58k orig miles. THM350 auto, 350 L48, JBM headers,Oyster White interior,.as of Nov '15 in process of painting.


Joined: 10/19/2015
Posts: 71

ED.. there are 6 phillips heads screws that hold the glove box interior in..and a bulb-socket.remove the 6 screws with a short phillips head screwdriver..two top front, two bottom front and one each side..remove lamp and wiggle remove the socket toward the cabin interior..then pull the glove box interior liner out..No need to fiddle with latch or hinges on box ..
Once you get the glove box liner out..look back behind atop the ductwork and you will see the bypass vac-solenoid mechanism.
.The control cable on the bypass is  coming from the hvac blower climate control console apparatus and is attached  to THAT  bypass..
The cable does several things..IT'S  the mech.temp selector connection from the hvac console unit..and ALSO  closes/opens the vac lines that lead to the heater hose underhood vac on off switch solenoid to shut off hot water from heater line and open defroster vent, A/C  vent etc. LOOK AT THAT BYPASS  switch and operate the temp control lever and SEE  IF  the cable is adjusted properly to CLOSE it and shut off heated water and open vac to vents..
IF it isn't adjusted properly.you need to remove the pass side console cover and use the turnbuckle on the temp control cable to get the adjustment right..
IS YOUR BLOWER WORKING?
IF it is do the above checkout BEFORE YOU REPLACE THE UNDER Console vac connections..jim
here's the colored link showing what does what..


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Re: Cannot change air flow location (8/8)
 7/17/16 5:31pm
jim in oregon
Former Member

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Milwaukie, OR - USA

Vette(s):
'78 Silver Anniversary T Top coupe,58k orig miles. THM350 auto, 350 L48, JBM headers,Oyster White interior,.as of Nov '15 in process of painting.


Joined: 10/19/2015
Posts: 71

Sarge81 said:
'81-'82's are the same Joel. Thumbs Up
I was looking for my diagram but you beat me to it.

Also read this and check that fitting/nipple  Click >http://www.docrebuild.com/dr-r-web/tip3.html







Doc Rebuilds diagrams are pretty accurate..but the one I linked to is much better!!IN addition knowing HOW to simply access the vac solenoids/switches for dampers is not readily published anywhere..Jim

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