76' C3 & no heat
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
76' C3 & no heat
Hello again. Well I've discovered that my car has no heat. the fan works ok, and the controls move up and down, but no heat not even a little bit. The car does have a "summer" thermostat (engine warms to about 200, no higher), and there is no cover on the flywheel (Previous owner had the car setup for drag racing). Even with a cooler running thermostat I still should get SOME heat, shouldn't I?
TIA
Dwayne
:cheers:
TIA
Dwayne
:cheers:
Melting Slicks
Joined: Oct 1999
Posts: 2,581
Likes: 14
From: Tolar Texas
Re: 76' C3 & no heat (DwayneHillier)
Maybe a previous owner had installed a water cut-off valve in the heater hose that goes to your heater core.
This is done to reduce the interior temperature during summer driving because the vacuum actuated shut-off valve installed from the factory often doesn't work too well.
This is done to reduce the interior temperature during summer driving because the vacuum actuated shut-off valve installed from the factory often doesn't work too well.
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
Re: 76' C3 & no heat (MIKER)
Hey Miker. Well I never would have thought of that. Given what you suggested, the hose running from the front of the engine on the passengar side to the firewall is the heater core hose? If that is it I found no valve; however there is a thing that looks like a, geez how do I describe it. looks like a disk with a wire comming out of it (I take it thats the vacuum shut off, thingy), I assume that is the valve from the in dash control to turn the heat on, no? Sorry if this seems like I don't know about cars, well truth hurts. haha
Is there away to test if the vacuum switch is working?
[Modified by DwayneHillier, 4:08 PM 11/3/2001]
Is there away to test if the vacuum switch is working?
[Modified by DwayneHillier, 4:08 PM 11/3/2001]
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
Re: 76' C3 & no heat (paul79)
Thats it! I was just looking at it actually, thanks Paul! Anyway to test that puppy if it works (albiet, if I get heat it works :lol: :lol: ). I guess if I let the motor heat up, then test the temp of the hose before and after the vacuum switch, while actuating the climate control I coiuld determine weahter the switch worked, I guess?
[Modified by DwayneHillier, 4:21 PM 11/3/2001]
[Modified by DwayneHillier, 4:21 PM 11/3/2001]
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
Re: 76' C3 & no heat (paul79)
Paul both hoses running to the firewall as per your pic. is cooled after letting the motor warm up to 100 Deg. Does this mean the valve is faulty?
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: 76' C3 & no heat (DwayneHillier)
Not necessarily. The valve opens by vacuum from the console control. No vacuum, no valve opening, no heat: no flow of hot coolant to the heater core. Just remove the white hose at the valve end and see if you have suction. Use finger or tongue. If you do, the valve is probably faulty. If you do not, then you will have to find the vacuum leak. Those valves are pretty universal Chevrolet at your local auto parts stores.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: 76' C3 & no heat (DwayneHillier)
I am out for the evening now but I just noticed that you are in Ontario. GM Canada will have that valve if you do not mind paying an outrageous price. Or you can try Canadian Tire. They have been very aggressive in the last year or so in catering to boomers like me and their older cars. If they do not have it in stock they can source it from the USA in about two days. And they basically swallow the 0.63 dollar differential. If you wish to go the most inexpensive route, go to Home Depot and get a manual on/off plumbing valve. You will then have heat or no heat. That hose is either 5/8" or 3/4" inside diameter. I do not recall which the upper and lower are. And my car is in winter storage so I cannot do a measurement. But good luck in solving that problem. Let us know how you make out. I like it when people end their posts rather than just leaving contributors hanging. It is simply a courtesy to those who take the time to say a fews of help :).
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
Re: 76' C3 & no heat (paul79)
Ok, I do not have succsion at the valve; however I do have sucsion on the t joint for the vacuum hoses above the Master break cylindar. The vacuum hose from there goes to a "thing" that is mounted almost in the sentre of the top of the firewall, there are two vacuum hoses there. One comes from the T joint, which I assume is the vacuum main, and another comes out of this "thing" which is connected to the valve, anyone know what that is? Can it be bypassed as there is no leak in the system, as when the engine is off, I still have a vacuum at the T joint for the Vacuum hoses. Thus I assume there is a problem in this "thing" against the firewall, which I assume is controlled by the climate control system, (lots of assumptions).
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: 76' C3 & no heat (DwayneHillier)
Too many assumptions, Dwayne. I think you are referring to the headlight vacuum system. The little white cylinder in the pic is the filter for the headlights near the brake booster. Leave it alone. Do not BUBBA a fix from there. It will have residual vacuum after the engine is turned off from the storage canister near the front bumper. The heater system is on a different circuit. Perhaps someone has a vacuum map for the 1976. If not I will find one tomorrow for my 1979 and perhaps we can find out what is the problem. It sounds like the heater control console but?? You should hear a "hiss" when moving from "OFF" to "HEAT." That is the vacuum taking over for the heater control valve I showed earlier.
Team Owner
Joined: Jun 2001
Posts: 43,136
Likes: 155
From: Thomson Georgia
Re: 76' C3 & no heat (DwayneHillier)
My hoses(heater) where suffed in the frame and they WERE not hooked up because the heater core was leaking....I had to replace the heater cor and hosed....NO Fun..I hope that is not the case for ya!!!
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
Re: 76' C3 & no heat (paul79)
Thanks Paul. I tried to Bubba fix you had mentioned for the valve, replaced it with a water valve, I actually get heat now, and there is no leak in the heater core :) . However, I did take apart the center console to troubleshoot the vacuum controlled valve. Only problem is, now I get heat but the fan is now blowing fuses. I was very carefull moving things around in there [console] but I don'tr know what is wrong, the fan will work for a few seconds almost a minute maybe longer, then the fuse blows (25A). I would also like to mention that the bubba style fix was a simple fix, though not a permanent one. As for hearing a hissing sound from the console, the only time I got a hiss, albiet faint was when moving the left control (system setting) from defog to the center position, other then that no hiss.
Thanks again Paul.
Thanks again Paul.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: 76' C3 & no heat (DwayneHillier)
That is difficult to understand. The blower motor is on a separate 25A circuit and the only wiring under the console (for the blower) is the three wire plug to the blower switch. And you cannot put that on backwards because of the pin configuration. Perhaps the plug is loose?
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,826
Likes: 0
From: Why Drive When you can ride
Re: 76' C3 & no heat (paul79)
I didn't try to take off the wire harness to the actual switch itself, but perhaps in moving things it became loose I guess that could cause a short, though it's a slow burn short in that it takes almost a minute to burn. Thanks again Paul, I must get together with you one day and talk shop over a few, and to thank you for your dilegence.
Thanks again
Dwayne :cheers:
Thanks again
Dwayne :cheers:
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: 76' C3 & no heat (DwayneHillier)
Just a last tip. Most of the electrical connections I have attended to intentionally or through component replacement have received a light touch of di-electric grease. This prevents corrosion and promotes electrical conductivity. This is the conducting lube that is used under HEI distributors control modules for heat transfer. You may wish to hit that blower switch connection to get good contact. A tube lasts forever. At Canadian Tire it is called spark plug boot lubricant. Works wonders.
[Modified by paul79, 9:10 PM 11/4/2001]
[Modified by paul79, 9:10 PM 11/4/2001]