heater core blend door
Thread Starter
Racer
Joined: Aug 2002
Posts: 269
Likes: 0
From: Lexington ky
heater core blend door
Can I get to this under the dash and test it in an 81? I am not getting any heat for some reason out of the vents but from the engine compartment hoses both being hot I can tell coolant is flowing through the system. Any suggestions, i want to drive to work tomorrow but i need heat? 
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
You should be able to at least get to the lever on the top of the heater box...its where the cable attaches. See if it moves.Unfortunately you can't get to the door without removing some ducts.
Jim
Jim
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
it might help if you take the glove box out as well as some ducts. They're not hard to remove and it would give you a look at most of the system...
Looks like this (click to enlarge)...
Looks like this (click to enlarge)...
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
I am in the process of re-doing my 72 roadster. I found the mount for the VACUUM control valve on the blend door to be broken on a 67K mileage Vette. You could possibly have the same problem. I was origionally going to change out my heater core (car has factory A/C.) I am now replacing the entire unit with an aftermarket A/C replacement (originallity be DA*NED! even if it is rare for A/C on a roadster.) This job is a major PITA on your Vette, have "fun" like I am.
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Burning Brakes
Joined: Aug 2005
Posts: 1,126
Likes: 0
From: Hudson Falls, N.Y. 76 Vette Modified L-48
Originally Posted by jac1502
Can I get to this under the dash and test it in an 81? I am not getting any heat for some reason out of the vents but from the engine compartment hoses both being hot I can tell coolant is flowing through the system. Any suggestions, i want to drive to work tomorrow but i need heat?
Thread Starter
Racer
Joined: Aug 2002
Posts: 269
Likes: 0
From: Lexington ky
Funny, I see your point but I am just very picky and like everything working the way it should!
QUOTE=kb2fzq]You say the hoses were "hot"...were they "I can't keep my hand on the both hoses" hot....or just warm? Was one hose "real hot!!" and the other "kinda warm"?...it's acting like core problems, if it is a cable activated door...if it's vacuum activated, I say look for a imtermittent vac leak...as in "bump" vac hose off..."bump" vac hose on...and if all else fails, buy a down jacket and drive...you're in Kentucky, come up here, I'll show you what cold really is...[/QUOTE]
QUOTE=kb2fzq]You say the hoses were "hot"...were they "I can't keep my hand on the both hoses" hot....or just warm? Was one hose "real hot!!" and the other "kinda warm"?...it's acting like core problems, if it is a cable activated door...if it's vacuum activated, I say look for a imtermittent vac leak...as in "bump" vac hose off..."bump" vac hose on...and if all else fails, buy a down jacket and drive...you're in Kentucky, come up here, I'll show you what cold really is...
[/QUOTE]
Drifting
Joined: Oct 2003
Posts: 1,426
Likes: 1
From: VetteMOD
St. Jude Donor '05-'07
On an 81 the door is operated by a cable but the lever (on the heater box) that the cable is attached to also operates a vacuum switch. Should be a white plastic body with a plunger sticking out of the end and two vacuum lines attached. This vacuum switch closes the water valve. If it is stuck there will be no vacuum to the water valve and it will stay closed regardless of the door blend position. To check it, take the line off the water valve and see if you are getting vacuum with the temperature setting on full cold and full hot.
Thread Starter
Racer
Joined: Aug 2002
Posts: 269
Likes: 0
From: Lexington ky
I pulled the glove box out and found that the cable for the blend door was unhooked so I connected it and now all is well. I did notice that the blend door lever is not coming fully in contact with the vacuum switch on top of the heater core. What does that vacuum switch do? I bent the lever some but not enough.
Drifting
Joined: Oct 2003
Posts: 1,426
Likes: 1
From: VetteMOD
St. Jude Donor '05-'07
Originally Posted by jac1502
I pulled the glove box out and found that the cable for the blend door was unhooked so I connected it and now all is well. I did notice that the blend door lever is not coming fully in contact with the vacuum switch on top of the heater core. What does that vacuum switch do? I bent the lever some but not enough.
Thread Starter
Racer
Joined: Aug 2002
Posts: 269
Likes: 0
From: Lexington ky
At first that is what I assumed it went to but the vacuum to the shut valve was working and coming on and off when the lever was not hooked up. Can someone confirm the vacuum switches function? Or is it just a strange corvette oddity? Gotta love it
