C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette
Sponsored by:
Sponsored by:

Cabin Air

Thread Tools
 
Search this Thread
 
Old Dec 30, 2018 | 01:11 PM
  #1  
psycho dad's Avatar
psycho dad
Thread Starter
Racer
10 Year Member
 
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
Default Cabin Air

Hey Guys,
I'm trying to get some air to blow into the passenger compartment (76 with AC).
The fan motor is blowing at 3 different speeds. I've removed the lower right dash and the duct work.

This door opens and closes and there is some air coming in. It's not very strong and when I attach the duct it dissapates to where you can't really feel it.
I guess there is blockage somewhere, any idea what I should look for?
Reply
Old Dec 30, 2018 | 03:01 PM
  #2  
psycho dad's Avatar
psycho dad
Thread Starter
Racer
10 Year Member
 
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
Default

May have found the problem. the lower edge of the heater box is covered in silicone, no bolt. There's got to be an air leak there.
Not sure I want to pull the box now.
Reply
Old Dec 30, 2018 | 09:38 PM
  #3  
kansas123's Avatar
kansas123
Melting Slicks
15 Year Member
Liked
Loved
Top Answer: 1
 
Joined: Sep 2006
Posts: 2,815
Likes: 470
From: Wichita Kansas
Default

Originally Posted by psycho dad
Hey Guys,
I'm trying to get some air to blow into the passenger compartment (76 with AC).
The fan motor is blowing at 3 different speeds. I've removed the lower right dash and the duct work.

This door opens and closes and there is some air coming in. It's not very strong and when I attach the duct it dissapates to where you can't really feel it.
I guess there is blockage somewhere, any idea what I should look for?
Does that door open and close, what does that? Just for my own edification... thanks, it must operate differently than a '72..... Can you fit your hand down there, it might be full of leaves or something?
Reply
Old Dec 31, 2018 | 04:30 PM
  #4  
psycho dad's Avatar
psycho dad
Thread Starter
Racer
10 Year Member
 
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
Default

the cable on top pulls it shut when I switch to defrost. I ran a vacuum hose as far as I could from both ends and didn't find anything.
I'm thinking heater box gasket now. With the silicone and mis-matched bolts I'm kinda scared it wont be able to get it back together.
BTW Kansas, I just saw your post for the LED instrument lights and ordered a set. Can't wait to get them in.

Last edited by psycho dad; Dec 31, 2018 at 04:33 PM.
Reply
Old Dec 31, 2018 | 06:15 PM
  #5  
BLUE1972's Avatar
BLUE1972
Race Director
15 Year Member
Liked
Loved
Top Answer: 5
 
Joined: Oct 2008
Posts: 19,220
Likes: 1,671
From: Long Island
Default

On the last few cars I worked on I found the A/C box full of debris and blocking the sir flow.

If you pull the resister out - you can look in with a scope and see if it's clogged.
Reply
Old Dec 31, 2018 | 06:20 PM
  #6  
kansas123's Avatar
kansas123
Melting Slicks
15 Year Member
Liked
Loved
Top Answer: 1
 
Joined: Sep 2006
Posts: 2,815
Likes: 470
From: Wichita Kansas
Default

Originally Posted by psycho dad
the cable on top pulls it shut when I switch to defrost. I ran a vacuum hose as far as I could from both ends and didn't find anything.
I'm thinking heater box gasket now. With the silicone and mis-matched bolts I'm kinda scared it wont be able to get it back together.
BTW Kansas, I just saw your post for the LED instrument lights and ordered a set. Can't wait to get them in.
You will love those lights
Reply
Old Dec 31, 2018 | 08:14 PM
  #7  
psycho dad's Avatar
psycho dad
Thread Starter
Racer
10 Year Member
 
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
Default

Originally Posted by BLUE1972
On the last few cars I worked on I found the A/C box full of debris and blocking the sir flow.

If you pull the resister out - you can look in with a scope and see if it's clogged.
I tried that, it was clean
Reply
Old Jan 1, 2019 | 10:02 AM
  #8  
BLUE1972's Avatar
BLUE1972
Race Director
15 Year Member
Liked
Loved
Top Answer: 5
 
Joined: Oct 2008
Posts: 19,220
Likes: 1,671
From: Long Island
Default

There is a conversion to use the C4 fan and motor which increases air flow. (a Lot)


C3's - there is a vacuum controlled flap in / by the A pillar under the right fender. This controls the inside air getting pulled into fan.

Last edited by BLUE1972; Jan 1, 2019 at 10:12 AM.
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

10 Ugly Corvettes That We Still Kinda Love

 Joe Kucinski
story-1

Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

 Brett Foote
story-2

10 Things Every Corvette Owner Needs (2026 Edition)

 Michael S. Palmer
story-3

8 Most "Only Corvette Owners Understand" Quirks and Problems

 Pouria Savadkouei
story-4

10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

 Joe Kucinski
story-5

How Much Horsepower Every Corvette Engine "LOST" in 1972

 Joe Kucinski
story-6

Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

 Michael S. Palmer
story-7

Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

 Joe Kucinski
story-8

150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

 Joe Kucinski
story-9

8 Coolest Corvette Pace Cars (and Replicas) of All Time

 Verdad Gallardo
Old Jan 1, 2019 | 12:46 PM
  #9  
psycho dad's Avatar
psycho dad
Thread Starter
Racer
10 Year Member
 
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
Default

Originally Posted by BLUE1972
There is a conversion to use the C4 fan and motor which increases air flow. (a Lot)


C3's - there is a vacuum controlled flap in / by the A pillar under the right fender. This controls the inside air getting pulled into fan.
down here by the fan?
Reply
Old Jan 1, 2019 | 12:59 PM
  #10  
BLUE1972's Avatar
BLUE1972
Race Director
15 Year Member
Liked
Loved
Top Answer: 5
 
Joined: Oct 2008
Posts: 19,220
Likes: 1,671
From: Long Island
Default

Reply
Old Jan 1, 2019 | 01:18 PM
  #11  
psycho dad's Avatar
psycho dad
Thread Starter
Racer
10 Year Member
 
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
Default

ah, thanks. I'll check that out
Reply

Get notified of new replies

To Cabin Air





All times are GMT -4. The time now is 11:33 AM.

story-0
10 Ugly Corvettes That We Still Kinda Love

Slideshow: 10 ugly Corvettes that we still kinda love.

By Joe Kucinski | 2026-06-03 10:34:17


VIEW MORE
story-1
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

A lot of money has changed hands at the online auction house over the years.

By Brett Foote | 2026-06-03 10:21:50


VIEW MORE
story-2
10 Things Every Corvette Owner Needs (2026 Edition)

Slideshow: 10 great gifts Corvette enthusiasts actually want for Father's Day!

By Michael S. Palmer | 2026-06-03 15:43:40


VIEW MORE
story-3
8 Most "Only Corvette Owners Understand" Quirks and Problems

Slideshow: These are the quirks, annoyances, and oddly lovable problems that every Corvette owner eventually learns to live with.

By Pouria Savadkouei | 2026-05-28 09:31:39


VIEW MORE
story-4
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

Slideshow: 10 reasons why the C6 Z06 is still a performance benchmark after 20 years.

By Joe Kucinski | 2026-05-27 17:20:09


VIEW MORE
story-5
How Much Horsepower Every Corvette Engine "LOST" in 1972

Slideshow: How much horsepower every Corvette engine lost in 1972.

By Joe Kucinski | 2026-05-27 16:54:53


VIEW MORE
story-6
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-7
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-8
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-9
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE