great68

Hey guys I have'nt had my vette but about a year and I took it out for a highway cruise the other day. In Texas about 80 degs top off. Its a 68 roadster 427 4sp. I don't have headers but the heat on the feet was kinda tuff. I tried to adjust the heat and a/c controlls but the heat was still tuff. Will assembly manuals show me whats under the dash? WHAT TO DO & WHERE TO DO IT!!!!

Big Block Dave

This is a popular topic with many associated symptoms that contribute to the entire problem of heat.

Do you feel any actual hot air blowing, or is it just ambient hot air that you feel eminating from the floor?

In short, you may want to consider laying down a heat barrier on your floor under the carpet...while doing this you may find other issues such as a torn shifter hole cover under the console, and other assorted access holes in the floor and firewall.

I grabbed some stuff called "reflectix" at Lowes and a scissor, carpet glue and reflective tape. Kinda finished the job towards the end of summer last year, but Im pretty confident that there was a difference

U17

Lots of information in here on different threads.... I got rid of the heat by installing Hooker Headers.... Takes the heat away from the firewall and no cast iron manifolds to store the heat in ....

great68

I think I felt actual hot air, though my wife said she just felt heat, but she had a large purse and another bag between her feet. I did feel like maybe the air was flowing from under the console. Do you know if the assembly manual shows the under part of the dash? Thanks Dave for the input and the pics!!

great68

I am going to put headers on real soon. I forgot about that old cast iron holding heat so bad. Thanks U17

U17

Forgot the best part ... sidepipes !!!

7T1vette

You could be getting engine compartment "blow-by" heat, if the rear hood seal is not sealing well, anymore. As those seals get compressed and dry out, hot engine area heat leaks out directly into the cabin air inlet ducting (cowl area at rear of right fender). To check, stick some clay or Play-Doh on top of the rear cowl lip where that hood seal will close. Close the hood, re-open it, and check how thick that clay/Doh piece is now. If it didn't flatten out completely, that gap is a 'hot air leak path' right into the cockpit.

P.S. The clay/etc. should be a thin section so it doesn't impose high resistance to closing the hood.

great68

Thanks 7T1 I'll check that! The right side is that the passenger side?

dbeall1968

I just finished exactly the same thing on my car. I was going to buy the stuff from Carlisle last year, and the lady selling it told me what can be bought at Lowe's was the same stuff, and about 20% of the cost.

PRNDL

gotta check all those pesky grommets on the engine side to make sure they are sealing the engine compartment. At night, lights out, shine a flashlight in the engine compartment and see if you see any light in the interior. A romantic 2 person job.

great68

I'll put a drop light under the hood and get my wife to crawl in and check for leaks!!! Thanks PRNDL

sweeet76

There is a rubber boot under the leather boot on the shifter. If that rubber boot has any holes in it, it will also let a lot of heat in.

great68

Thanks sweeet76 I will check that tomorrow.

Mashman

The most likely source of the heat is the heater core.

The blower on the C3's runs continueously, combine that with old seals that have most likely hardened, and cracked years ago, and it adds up with a very hot footwell.

The easiest solution to this, is to add manual hotwater cutoff valves onto the heater hoses. There are many threads on this, so if you do a search you will find many examples of what people have done. If you don't already have cutoff valves, or they are currently open, cutting off the water flowing to the heater core will make a HUGE difference.


http://forums.corvetteforum.com/sear...rchid=28981994

keithinspace

I'm having the exact same issue on my car.

Admittedly, I haven't been through the whole thing since purchased, but think I've traced MY biggest problem...

I let my Brother drive my car (with me in it) and I noticed a HUGE amount of heat coming in through the vent duct on the passenger's side footwell. The AstroVent? Doesn't come through the driver's side since this vent doesn't open. I haven't torn into the thing to find out why it opens or how to control it. I presume there is a bunch of header heat coming in from the outside by way of this vent.

I am running Hooker sidepipes.

Also, my HVAC doesn't work and don't know that I have any control over the air passing over my heater core. But the hot air is definitely coming out of this open side-vent and not out of HVAC piping.

Mashman

Are you talking about the vent ball, or the kick panel? Behind the kickpanel is a door. This door is only supposed to be open when the AC is on max - it opens, and the fresh air door up by the cowl closes - it is designed to pull in and recirculate already cooled air. If the door behind the kick panel is open, it's letting in hot air from the plenum.

Two main reasons the air in the plenum is hot are, 1) hot water is circulating thru the heater core. To stop this, the easiest way is to install manual cutoff valves. And, 2) the rear hood seal is bad, and hot engine heat is entering the cowl where it's pulled into the fresh air vent. To check the seal, put a piece of newspaper over the seal, and close the hood, if it pulls out easily, replace the seal.

Also, remember the blower motor is always on, so if there is hot air in there, it's going to get pushed out.

LemansBlue68

I found my air mixer door was stuck in a partially open position allowing some heat to blow all the time. I was in the middle of my frame off so I had the entire blower/heater/vent box out and disassembled. While there, I replaced the flapper door seals and made sure everything moved freely. There's a metal tang on the mixer door that moves the door between open and closed. That got bent by the PO when he tried to force the stuck door closed. I had to repair it, and while there, reinforced it. This is probably more work than you want to hear about getting into but it was a necessity for repairing my car properly. If you have an A/C car, things may be a bit different.

keithinspace

Kick panel. Honestly didn't know the fan ran all the time...don't hear it and nothing else about my HVAC is currently working, so I'm a little surprised by this.

I admit that I know next to nothing about this entire system. I'll probably go the route of figuring out the core cut-off for the near term, then getting into the "larger" project at some point in the future when I'm willing to tear the entire dash apart. Not ready to do that yet.

I wanted to post my issues just in case the OP finds that this is the exact same problem he has.

Keith

great68

Thanks Mashman and everyone else for all the input. I fixing to try it right now.

great68

Ok one question? I guess you put the cut off valve on the hose comming out of the water pump??