C3 Vette Registry - The Best Resource on the Net for C3 Vettes! C3 Vette
Forums -> C3 Cooling and Heating Systems
Not Logged In! Login or Register!  Users Online: 25 / Help 
Features  Find C3 Parts on ebay in only 2 or 3 clicks!  | Add YOUR C3 to the Registry

Supporting Vendors
VetteBookStore.com
Bair's Corvettes
Volunteer Vette Products
Mid America Motorworks
CorvetteClothing.com

C3 of the Month
None Current
Enter Yours Today!
Online C3 Show
13
C3s are Registered

Vanity Plates
ITSA 70
Norsky
Featured Links

Buy Now
Kindle
Kindle


How To Rebuild Corvette Rolling Chassis 1963-1982
How To Rebuild Corvette Rolling Chassis 1963-1982


Corvette 50th Anniversary
Corvette 50th Anniversary


Corvette Fifty Years (Hardcover)
Corvette Fifty Years (Hardcover)



| Hide Signatures and Profile Pics

 New Topic New Topic Post Reply Reply New Poll New Poll Search     Search Page [1]  
10/23/08 9:55pm - Original Message: 'Vacuum Leak'
tsmith1499
Former Member
- Send Private Message


mount airy, MD - USA

Vette(s):
1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.

Joined: 8/27/2006
Posts: 71

Where is the best place to start looking for a vacuum leak that affects the heater and defroster door from changing?  Once in awhile I can get the defroster to blow on the windshield, but mostly it blows on the floor and I just noticed today that I hear a vacuum sound through the defroster vent when it's on heat.  The sound goes away when put on vent or defrost.  What a time to start acting up, just when it starts to get cold.  Thanks, Tom



____________________________________
1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.
 Reply Reply  Quote Reply w/Quote
 
Support C3VR!
Suport our advertisers
10/23/08 10:05pm - Reply: 'Vacuum Leak'
Ron 78 Lifetime Member
Lifetime Member
Moderator
- Send Private Message


BINGHAMTON, NY - USA

Vette(s):


Joined: 7/19/2003
Posts: 3805
Whats that?a vacuum leak on a Corvette,impossibleLOL

____________________________________

C3VR Lifetime Member #93
 
 Reply Reply  Quote Reply w/Quote
10/23/08 10:14pm - Reply: 'Vacuum Leak'
acplus
Former Member
- Send Private Message


, - Canada

Vette(s):
1972, 1980

Joined: 6/23/2008
Posts: 558
Remove the glove box door and inside box, screws are on the side for the box, this will give you access to the top vacumn lines, remove the side panels on the center shifter console, don't forget the screws at the back beside the seat bottom side, this will give you access to the lower lines, check to see if one of the modules hasn't been unplugged or cracked.
John


____________________________________

1972 CORVETTE CONVERTIBLE BRYAR BLUE
 Reply Reply  Quote Reply w/Quote
10/24/08 8:32am - Reply: 'Vacuum Leak'
deeboy59
Former Member
- Send Private Message


visalia, CA - USA

Vette(s):
1981 red with silver interior,350(L-81), 350TH, glass t-tops, aluminium rims, 1980 Black/ Black int., 350 GM crate engine/350TH, 1976 black/ saddle int., L-82 w/headers, holly carb, Hypertech ignition

Joined: 10/27/2006
Posts: 641
I have the same problem on my '81.   I found it to be the vac. actuator for the defroster door which is mounted up under the dash on the drivers side.  On mine,  the diaphram had actually ruptured and was leaking air.  At first, it continued to work,  but then it slowly got worse and worse and you could here more and more air wissling thrjough the vent.  Beings I'm in California,  I dont need the defroster that much,  so I just disconected and pluged the line  and put that on the repair list ....Ermm HTH
 
 Daniel


____________________________________
"Speed is money, How fast you wanna go?"


(click to see a bigger image)
 Reply Reply  Quote Reply w/Quote
10/24/08 12:23pm - Reply: 'Vacuum Leak'
anips
Standard Member
- Send Private Message


sonoma, CA - USA

Vette(s):
72 LT-1 AC coupe,69 l-36 coupe

Joined: 8/9/2002
Posts: 783
If you have access to a electric vac pump hook it to the hose that comes from the vac tank, that way you can check everything without starting the engine to build vac, a friend of mine had a vac pump he used to evacuate AC sys's

____________________________________
 Reply Reply  Quote Reply w/Quote
10/24/08 8:10pm - Reply: 'Vacuum Leak'
acplus
Former Member
- Send Private Message


, - Canada

Vette(s):
1972, 1980

Joined: 6/23/2008
Posts: 558
Any luck?

____________________________________

1972 CORVETTE CONVERTIBLE BRYAR BLUE
 Reply Reply  Quote Reply w/Quote
10/24/08 10:32pm - Reply: 'Vacuum Leak'
tsmith1499
Former Member
- Send Private Message


mount airy, MD - USA

Vette(s):
1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.

Joined: 8/27/2006
Posts: 71
Haven't had a chance to look  at it yet. Hopefully this weekend. I will report on what I found.  I had another problem crop up yesterday. Coolant leak under front drivers side. At least that's where it's dripping from. Need to check them both out. If it's not one thing it's another.
Thanks for all the ideas,  Tom


____________________________________
1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.
 Reply Reply  Quote Reply w/Quote
10/25/08 12:41am - Reply: 'Vacuum Leak'
Gale Banks 80 Lifetime Member
Lifetime Member
- Send Private Message



Vette(s):
1980 with a Banks Twin Turbo 1969 Convert Big Block 1996 Grand Sport Convert

Joined: 9/8/2005
Posts: 241
 Go to Home depot and Buy a long Hose that You can run outside Your garage to another car. Plug in both cars and start the one outside. You will now be able to Here any Vacume leak and trace it down with out any Engine Noise.

____________________________________
My Car...PIC 1     PIC 2
 Reply Reply  Quote Reply w/Quote
10/25/08 5:54am - Reply: 'Vacuum Leak'
terntes
Former Member
- Send Private Message


Little Rock, AR - USA

Vette(s):
1982 Collector Edition

Joined: 7/10/2007
Posts: 116

I have the same defroster problem with my '82. I've checked everything except the diaphragm, which I am sure is the culprit. I can hear a return spring over-riding the initial vacuum to the diaphragm and slowly the defroster turns to a heater. I haven't fixed mine yet either, but this year for sure. Don't give up, these fine cars need a lot of TLC, but they are worth it.

terntes

 Reply Reply  Quote Reply w/Quote
10/25/08 7:34am - Reply: 'Vacuum Leak'
corvette440hp Lifetime Member
Lifetime Member
- Send Private Message


Joined: 7/2/2006
Posts: 8205
Here is something that you might want to check out;  http://www.corvette-101.com/vacuum.htm

____________________________________
corvette440hp
 Reply Reply  Quote Reply w/Quote
11/2/08 1:09pm - Reply: 'Vacuum Leak'
terntes
Former Member
- Send Private Message


Little Rock, AR - USA

Vette(s):
1982 Collector Edition

Joined: 7/10/2007
Posts: 116

tsmith,

  Have you tackled your defroster problem? I started looking for mine and I have found two actuators under the dash, according to the manuals. The one I can see actuates the AC door. The other one I can't see but I can hear it when I swithch to vent or defrost and it sounds like it is coming from higher and deeper in the dash. I removed the instrument cluster and I could see nothing. Have you had any luck?

terntes
 Reply Reply  Quote Reply w/Quote
11/2/08 2:43pm - Reply: 'Vacuum Leak'
acplus
Former Member
- Send Private Message


, - Canada

Vette(s):
1972, 1980

Joined: 6/23/2008
Posts: 558
I believe you will find your other actuator behind the guage cluster center console, or try removing the glove box first to gain access to see if a hose has a problem.
John


____________________________________

1972 CORVETTE CONVERTIBLE BRYAR BLUE
 Reply Reply  Quote Reply w/Quote
11/2/08 4:06pm - Reply: 'Vacuum Leak'
terntes
Former Member
- Send Private Message


Little Rock, AR - USA

Vette(s):
1982 Collector Edition

Joined: 7/10/2007
Posts: 116
acplus,
  Thanks for the post! I had both cluster and glove box out today and immediately behind the center console instrument cluster is an air distribution box. It must be buried behind the box. I can't see anything more with the glove box out. So, I put it all back together and will tackle it again when I have time to dig deeper.
terntes
 Reply Reply  Quote Reply w/Quote
11/2/08 4:19pm - Reply: 'Vacuum Leak'
suncountry Lifetime Member
Lifetime Member
Moderator
- Send Private Message


Moses Lake, WA - USA

Vette(s):
1976 L48 4-spd, Mahogany Metalic exterior, Buckskin interior 350ci/350hp, 3rd owner, fiberglass spring, 255/50-16's Torq-Thrust II

Joined: 4/16/2005
Posts: 2134

Something else to consider is the air valve its self that the controls the heater doors. It could be plugged up with dust and dirt from years of use if there was a bad diaphragm.



____________________________________


Full Size
C3VR Lifetime Member #110 We are all young at heart Glen
 Reply Reply  Quote Reply w/Quote
11/2/08 10:41pm - Reply: 'Vacuum Leak'
acplus
Former Member
- Send Private Message


, - Canada

Vette(s):
1972, 1980

Joined: 6/23/2008
Posts: 558
Were you able to hear the vacumn leak any louder to hear if that is the area it was coming from?
John


____________________________________

1972 CORVETTE CONVERTIBLE BRYAR BLUE
 Reply Reply  Quote Reply w/Quote
11/3/08 7:24am - Reply: 'Vacuum Leak'
terntes
Former Member
- Send Private Message


Little Rock, AR - USA

Vette(s):
1982 Collector Edition

Joined: 7/10/2007
Posts: 116
  Unfortunately I did not start the engine while I had the instruments and glove box ou, by that time it was time to quit playing with my car and grab a paint brush and help my wife!
  My diagram clearly shows the actuator to be back in there somewhere so, it will have to wait 'til next weekend.
Terry.
 Reply Reply  Quote Reply w/Quote
11/3/08 7:28am - Reply: 'Vacuum Leak'
terntes
Former Member
- Send Private Message


Little Rock, AR - USA

Vette(s):
1982 Collector Edition

Joined: 7/10/2007
Posts: 116
  I do have other issues with the system, max air works great but normal air does not blow hardly any at all from the ac duct but blows good through the heater ducts. My vent hisses and I get nothing, the heater blows good but, when I switch to defrost it blows good at first then within seconds it dimishes to nothing but the heater duct.
  I need a complete trouble shooting chart to determine what is affecting what!
Terry.
 Reply Reply  Quote Reply w/Quote
11/3/08 11:09am - Reply: 'Vacuum Leak'
corvette440hp Lifetime Member
Lifetime Member
- Send Private Message


Joined: 7/2/2006
Posts: 8205
Check this out..........I hope that it might help:   http://www.corvette-101.com/vacuum.htm I know that this is a headlight procedure check, but as you see you can use a vacuum pump tool to check things out.corvette440hp2008-11-03 10:35:34

____________________________________
corvette440hp
 Reply Reply  Quote Reply w/Quote
11/3/08 6:54pm - Reply: 'Vacuum Leak'
tsmith1499
Former Member
- Send Private Message


mount airy, MD - USA

Vette(s):
1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.

Joined: 8/27/2006
Posts: 71
I finally found my problem this past weekend. Hose had cracked and had come off at a connection. I lubricated doors and put everything back and it works fine now.  Until the next time when it doesn't work fine.  LOL I printed out the headlight diagram got future use.  Pretty cool!  Thanks, Tom 

____________________________________
1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.
 Reply Reply  Quote Reply w/Quote
11/3/08 8:24pm - Reply: 'Vacuum Leak'
acplus
Former Member
- Send Private Message


, - Canada

Vette(s):
1972, 1980

Joined: 6/23/2008
Posts: 558
Good going. John

____________________________________

1972 CORVETTE CONVERTIBLE BRYAR BLUE
 Reply Reply  Quote Reply w/Quote
 New Topic New Topic Post Reply Reply New Poll New Poll Search     Search Page [1]  
 Forums -> C3 Cooling and Heating Systems
(Moderator: Adam Wartell, Norsky, Adams' Apple)
 

 
Official C3 Vette Registry Community:
Home | Forums | Email | Who's Online | Clubs | Events | Member Stats

Other Official C3 Vette Registry Areas:
Members | Research | Shop | My Account | About C3VR
 

Corvette is a registered trademark of the General Motors Corporation(GM) & Chevrolet Motor Division. Vette Registries, LLC is responsible for all site content (except for member submitted content or where otherwise noted) and does not claim or imply that Chevrolet or GM is responsible for Official C3 Vette Registry content. Vette Registries, LLC is independent from GM and is not affiliated with, sponsored or supported by GM.  Copyright/trademark/sales mark infringements are not intended, or implied and are in fact used to support GM, Chevrolet and Corvette

Official C3 Vette Registry content is Copyright 2001-2017, Vette Registries, LLC. Content may not be reused without written consent. All Rights Reserved. NS

Corvette (Vette) Model Years on this site: 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 30