Outside Air vent

[Buckskin7T7V]

Where does the outside air , come in to the air vent, on a 77? It has A/C, so the foot vents do not function. The air comes out of the A/C outlets.
I have a reading of 70 degrees outside temp, and by time it gets into the passenger compartment, it become 90 degrees. Where is all of this air getting heated up at?

 

[Bob Chadwick]

My understanding is that it comes in at the bottom corners of the windshield pillars in that "tray" with the windshield wipers. Does your hood have a good rear seal? If not, heat comes from the engine compartment and is drawn in here.

There are other sources of heat as well but that is an obvious one. For example, is your heater control valve working, is the temperature control door properly adjusted, etc?

Bob

 

[Buckskin7T7V]

I did replace the hood gasket and added a hot water shut off "manual" value in the water line. I did not check the temperture control door.

 

[Bob Chadwick]

I had warm air coming in from there as well.

Did you install a manual valve or replace the vacuum controlled valve. While the vacuum valve was working I suspect some leak by that was heating the air and until I had the door adjusted, was allowing heated air into the cabin.

It runs cooler with all of these repairs but it still gets hot in the cockpit without the a/c on. Part of my problem is the heat radiating from the drive shaft tunnel. After running for a while, this gets hot to the touch, I would guess 90 degrees or higher. My carpet needs to be replaced and when I do this, I will make sure I go with the best insulation package I can find.

I don't know the answer to this but perhaps heat is being transferred into your ventilation system from a similiar heat transfer.

JSimpson told me about a the book "Air Conditioning Strategies for the 63-82 Corvette" by Michael J. Davis and highly recommended it. I have it on back order. Once I get it, I'll take a look and will post any good tips that have not been touched on before.

Bob

 

[Buckskin7T7V]

Thanks for the info. I replaced all of the carpet and installed heat shield material under the carpet. It helped. The best stuff is "KOOL MAT". Problem is, it cost a fortune. I did spary the drive line tunnel with consumer grade undercoating, when I did a complete redue on the car. I wish there was a way of getting the heat out of there. I will look forward to any info you might come across when the book arrives. Have a good one and Thanks again.

 

[Bob Chadwick]

Where did you get your KOOL MAT product from? Did you order it pre cut or did you cut it your self? If you cut it your self, how much did you need and what did it cost?

Bob

 

[Buckskin7T7V]

I did not buy this yet. Great stuff, cost is on the high side.
http://www.koolmat.com/main.htm

 

[Bob Chadwick]

I was at their site as well. I also saw some precut kits but the prices were out of this world, with one in excess of $300.

Bob

 

[Buckskin7T7V]

I think I will buy NASA cool suit this summer. Have a great week-end.

 

[fc3]

I have a hot air problem with my 72 with A/C. I am just beginning to fix the problem, have only had the car a few days!

 

[Bob Chadwick]

What are you doing FC3? I ran mine today, the a/c is great but the longer you run the car, the less cooling affect from it. Some of the stuff is obvious. For example, the drive tunnel is hot to the touch and when I change the carpets, I'm going to make sure that gets well insulated. This is radiating a ton of heat into the car and the a/c is fighting with it. Other stuff not quite so. Give us some insight on what you are doing.

Bob

 

[Buckskin7T7V]

I am lost, except for also insulating the drive tunnel. Do you have a 4-speed or auto transmission? My is a 4-speed. The auto do have a heat shield that goes over the top of the tranny. What about the "Thermoglass Exhaust Wrap"? Mid- America sells it and you wrap your exhaust pipes with it. I thought I read somewhere, that there is a problem with using it. I think I have sealed all of the little openings in the firewall. I know that the rubber boot around and under the shifter can let in a lot of hot air.

 

[Bob Chadwick]

I'm in the process of pulling trim pieces and dying. I've got almost everything out of the back, which brings me to the next project, replacing the carpet.

When I do this, I'm going to heat seal everything that I can reach. Anybody else have a comment on Kool Mat or a competing product? If you use this, do you still put the padding, which I understand shields some of the heat, down as well.

I ran mine yesterday in high 80 heat with the a/c on. I loose a bit of cooling as the day goes on. I opened the hood and the box that holds the evaporator, I think that is the unit on the firewall, was very hot. Has anyone insulated this to keep the heat off it?

Bob