vet85

ok im in the market to purchase me a 77 .but ive had a couple and a buddy has a 76 and the inside temp is horrible .is it the door to the heater or do these year models just put of excessive floor heat .i just really dont want to get one if everyone just says deal with it .id rather get another one .but if its a repairable problem .well im game to fix it .i just like the 77 model cars .so : any suggestions would be very helpful thank u .

rcread

It could be the hot antifreeze circulating through the cabin. You can install a cut off switch in the heater hose in the engine compartment. The foam piece that goes between the firewall and bellhousing might be missing. The insulation between the transmission tunnel and the transmission could be missing. You should be able to fix whatever the problem is.

Ganey

I don't find a problem there w/ my 77. Some have posted the heater control valve in the hose was removed so they had to fix that or seals were bad or missing like in firewall or console shifter.
I have factory A/C.

rcread

They didn't have this problem when new. My parents bought a new '77 when I was 10 (they still have it) and the cabin was never unusually hot. My '71 convertible, which is missing the seal between the firewall and bellhousing and doesn't have a water shut-off valve gets REALLY hot inside the cabin. I'm addressing this with a Vintage Air unit and I'll install the seal when I put the new engine in.

Petes73

The seal between the heater box and the firewall will fall out leaving a gap that allows heat to pour into the cabin.

vet85

for ur answers im going to start looking again .if yours is ok then it must just b fixable

jcloving

It's fixable. The Chevy 350 radiates lots of heat. It converts some of the fuel energy into waste heat and that gets radiated thru the firewall.

Plus the heater core could be trickling in some fluid. The fan always blows on corvettes so hot air could pour out of the vents.

The most popular solutions are to put a manual shut off valve on the inlet hose to the heater core and to put heat insulation like reflectix under the carpets. This will take care of most of the problem. The small gains are things like firewall holes, cowl vent seals etc.

I did the stuff above and my temps are way, way down. Now I'm trying to get my AC really cold to fill my cooler cabin with frosty air.

terry82

i found lots of places for heat to come inthru the firewall .i fixed those and the heater cut off ,and new insulation on the floor boards.car is fine now .

Ganey

I changed mine to turn the fan off instead of low though not because of heat.

Danish Shark

I've been wondering why the fan is running when heat/AC is off.
What's the purpose of that?

P.S Both my 69 and my 71 have the vacuum operated cut off valve (and new seals in the heater box) and they are both nice and cool with the heater shut off.

Mick71

My non AC '71 coupe is black on black with all the seals in place isn't bad at all, even with the latest hot weather we've been having. Vintage Air is on my to do list, though.

psycho dad

I just applies home made lizard skin to the floor pans, it made a big difference. I still need to tackle the heater core gasket, but that can wait till winter.

Hodge

This is what I did on my 73:

Fixed obvious air leaks in the a/c system (evaporator housing to firewall, the seals where the evaporator tubing comes out of the housing, and the condensate drain cover was missing)
the fresh air door on the pass side footwell was broken. I removed it to prevent out side air entering the cabin
Put cutoffs in the supply and return heater hoses
Repaired obvious holes/air leaks in the firewall

All the above helped a lot but the original a/c still would not cool properly. It made driving in the summer tolerable. My permanent fix was ordering a vintage air setup two days ago.

Jud Chapin

Be sure to check the weather stripping on the rear of the hood. If it's not sealing properly, hot air from the engine compartment will be sucked into the duct work.

noonie

That's the biggest culprit besides the blend door in the housing and the hot water being circulated thru the heater core.
The bond between the fender and the firewall often cracks allowing hot engine air to enter the return plenum on the passenger side.

Bad seals in the evaporator housing won't cause hot air intrusion because it it on the pressure side of the fan. You just loose air volume to the interior. Turn the fan on high and you will feel fresh or interior air being blown into the engine compartment.

All are pretty easy fixes to keep the interior cool.

a17mike

I put a clamp on the heater hose in the summer and I installed Dynamat when I replaced the carpet this last winter in my '72.

Made a big difference per the prime passenger.

Mike

Rich's'78

I believe all cars must have the fan runing on a slow speed in case you have an exhaust leak under the car which could draw in carbon monoxide (odour - less poison).

udornf4

Very poorly documented in the Assembly Manuals - is the grommet that the parking brake cable goes through (under the forward part of the Parking Brake console).

Mine was totally gone - and hot air really comes in there if you don't have that grommet.

my .02

billcarson

my 76' fan does not run unless the heat or ac mode is chosen.this may explain a lot of things.

LastC3AZ

I found the heat / cool control cable from the console was broken where it connected to the flap door it controls ... behind the glove compartment ....
since we don't need much heater action here ... I simply tied the door control to the closed position ... done deal !!!