New 1976 Owner with Limited Skills

Group - I just bought my first Corvette -1976. I have no experience with working on cars at all, but am a fast learner. I drove it home last night and found out that the heat doesn't work. I'm not sure where to begin to search for the problem. Is this something that I can fix myself or should I take it to a mechanic?

For diagnostic purposes - the fan blower works and both dials on the control panel move and air flows both at the top and bottom. I put it on defrost, heater, and vent and had the same frigid results.

Any help will be appreciated...

Reply to
1976VetteGuy
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what about the temp slide bar ? Does it work ? are you sure that the heater core has NOT been bypassed ?

Reply to
'Key

The temp slider does move, but I don't know if it's doing anything. Is there an easy way for me to tell if it's actually moving the proper door?

As far as the heater core being bypassed...I have no idea and don't really even know what that means, so any enlightenment would be helpfull!!!!

Thanks

Reply to
1976VetteGuy

What's the temperature gauge read?

1976VetteGuy wrote:

Reply to
Just another guy

Here's some diagrams that might help you understand what's in your car:

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Look at the diagram at the bottom center of the page and note the unlabeled device at the top of the picture... that's a metal diverter valve that sits in the engine compartment and has heater hoses connected to it. The heater hoses are attached to the nipples shown at the top and right coming out of that valve, the small hose shown as white in the diagram is a vacuum hose that actuates the diverter valve to send hot water through to the heater core under the dash when you turn on the heater, or to bypass the heater core and send the hot water back to the engine.

note: This particular picture shows a system without a/c, but I believe that same valve is present on cars that DO have a/c as well, but they just don't show it on the a/c diagram (upper left on the page), they only show the airflow door actuators. I don't have a C3, so I can't verify that.

That valve can stick or become disconnected from the vacuum hose, or there could be a leak in the vacuum system that prevents sufficient vacuum from reaching the valve. It is a common point of failure. The valve is not particularly expensive to replace.

It could be checked by applying vacuum directly to the valve to see if the heater then works (you should be able to feel that the water hose from the diverter to the heater is cool before vacuum is applied, then heats up with vacuum applied). You may need a vacuum pump to test with, or you can "borrow" vacuum from another vacuum source on the engine by "Tee"ing into that good vacuum source. (Simply sucking on the hose orally is not likely to produce sufficient vacuum.)

You could also disconnect the two water hoses from the diverter valve and clamp them to opposite ends of one short section of copper tubing (5/8" I believe) to bypass the valve for the winter, then reattach them to the diverter valve in the spring.

Good luck.

Reply to
WayneC

Reply to
WayneC

The temperature guage reads pretty low. It barely creeps up, but I don't even know if it works or not...

This group rocks!

Thanks to everyone so far...good stuff!

Reply to
1976VetteGuy

wow...thanks for the detailed answer. I'll check that out tonight when I get home...

Reply to
1976VetteGuy

VetteGuy: Actually I am betting that the heater has been bypassed ... Honestly these cars do not get driven in cold weather much anymore and can get really "warm" inside in the summer... so many ...if not most.. owners bypass the heater..

BUT ... I would check out the C3 registry

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and take a free ride for a month or pay all of 10 bucks for a years membership...

Honestly it is the absolute best source of info(AND FREE ADVICE) on

68-82 Corvettes ..I own 3 C's and am a LIFETIME menber ONLY because everytime I had a problem I GOT ANSWERS...

Enjoy the car.... and BTW...they are very simple to work on... mo high teck computers ...only real problem that the very first step to do any repair usually is DISMANTLE THE ENTIRE CAR... LOL

Seriousl check out the registry...its full of forums that deal with everything from electrical to mechanical problems.. I did not drop the money to become a lifetime menber just for the fun of it...I got so much help with my first C3 that I saved lots of Time BUT also lots of money...

Bob G.

64 72 & 98 Convertibles 76 & 79 Coupes...

============================

Reply to
Bob G.

If the temperature gauge is reading low, you may need a new thermostat. Replace it. Costs less than $20. You need the engine to be at working temperature before you'll get any heat.

1976VetteGuy wrote:

Reply to
Just another guy

Well it may be as simple as manual heater control valve that's in line on the heater hoses. You turn it off in the summer and on in the winter. Whomever designed the nice heater setup on the 70's GM products needs to go back to school, I'm sure that person is most likely not around any more. My 78 Z28 pumped hot air into the car in the summer when the A/c was not on. I finally got tired of that and installed the above referenced manual heater control valve. I don't believe that the camaros or corvettes had a vaccum or other type heater control valve on the heater hoses during the late 70's.

(1) check to see that the heater hoses are connected to the firewall, there are two.

(2) check coolant level to make sure car is full.

(3) let engine run and get to operating temperature (what is that temp?)

(4) check to see if both heater hoses at the fire wall are hot...after engine runs a while.

(5) check to see if previous owner installed a manual heater control valve or "by-passed" the heater core.

(6) if all good above....then look for issues with the A/C -heater control head, broken cables, broken temp door, etc. I'm not sure on that model but it may have vaccum operated heater and A/C temp door controls, or it may be the old school pure manual setup.

You have to "have" hot coolant at the heater core....for heat, that's the first thing to verify.

----------- Elbert snipped-for-privacy@me.com

Reply to
Elbert

On Mon, 26 Nov 2007 12:36:22 -0800 (PST), 1976VetteGuy wrote something wonderfully witty:

Do three things. No particular order.

  1. Find your local Corvette Club. They're everywhere ask the local Chevy dealers. A lot of them meet there.

  1. Buy a Chiltons or similar.

  2. Get a decent entry level set of tools, I suggest Sears on that one.
Reply to
The Wolf With the Red Roses

Thanks...I don't think it was bypassed, but not sure. I actually don't even know where the heater core is located...I assume it's behind the firewall??? So if you have the time, can you get more detailed and tell me how to check this as I have replaced the thermostat and made sure it has enough coolant. I'm pretty sure it either a hose or heater core problem of some sort. I wouldn't know what the bypass would look like. I can't even find the damn water pump. I bout a new one, but my future father-in-law says that I would know if it was bad as it would be noisy and the car would overheat. So I need to find that so I can follow the hoses to the heater core? The guy at Autozone said that I should try to clean/flush out the cooling system...to try to clean out any gunk or rust that may be in there???? I bought a kit and a solvent to flush it with, but don't want to go throughg the trouble if I don't have to....???? It would be a cheap fix if it worked...

Is the heater core hard to get to???

Thanks for your help...

Reply to
1976VetteGuy

The other possible solutions are much easier to try. I've done the heater coil, A/C, and pretty much everything else on my 1982. The heater coil fits through the firewall. The first step in the repair manual is to remove the seats, dash, and everything over the interior part of the heater coil. The second step involves removing the parts in the way under the hood. A good mechanic will charge about $500-700 for the day it will take to replace it. Start by finding a repair manual for your 1976.

David

Reply to
Eagle

I bought the C3 (it says like 1966-1976 Shop Manual in red on the cover) Shop Manual, but am very disappointed in the content. What are the best shop manuals out there?

Reply to
1976VetteGuy

I have both the 1982 Shop Manual and Chilton's. They do leave much to be desired. My mechanic subscribes to the Mitchell Repair Manuals as well as many others. Perhaps Mitchell has a limited distribution you could buy. I'd suggest finding a local mechanic (Master Auto Technician) and asking him/her. They will likely help describe the process or let you look at manuals. My mechanic would let you do it yourself, off hours, with his tools for a pittance.

David

Reply to
Eagle

my local library subscribes to the mitchell database. one can use it for free at the library.

regards, charlie cave creek, az

Reply to
charlie

The GM shop manual is the only manual I've ever found that worth buying. The others skip to much material or leave key steps and areas "unexplained"..

----------- Elbert snipped-for-privacy@me.com

Reply to
Elbert

Where can I get the GM shop manual?

Reply to
1976VetteGuy

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