Bond007

Hello Fellow Vetteheads, Need some advice on what to do about the heat in the car. It appears that my heater control valve does not work or the vacuum is the problem, either way I get a constant flow going to the heater no matter if I select air conditioning or not. I am under the impression that when the air is selected the heater control valve should close. I pulled the vacuum tube off and tried to get a sense of a draw on the hose, but it may be so slight that I probably would not feel it, so is it the vacuum or the valve? My feeling is to put a valve on each end of the heater off the block and bag it in the summer and in the fall on nice days valve them in when going for a ride, that's when it gets cool up here, what if any is your take on this? Thank You All in Advance.
Peter

rihwoods

Try this first...check very carefully the tiny vacuum line(from firewall down to valve). Mine got brittle over time(near valve),and caused same thing.You can cut out bad section,and insert a rubber hose piece onto both ends of the original...I can get a digital/post here,if you like...
Rich

Edit.....here is pic of my fix..



I ran new line down to valve.... (Next, I need to replace "puke" tank)....

71406

I'm not sure about a 76, but on the 71, the heater control valve was designed to only close in the MAX position for the A/C.

tallgirl

Go to your local parts place and 1). buy a vacuum guage, 2). buy a vacuum pump.

The guage should be able to measure the vacuum, even if the maximum flow of vacuum-ness (heh) isn't all that great, as it often is with vacuum motors. The pump can be used to determine if the valve is good or bad. My is a hand-operated squeeze-thingy with a built-in guage. One or two quick squeezes usually draws enough vacuum to operate any vacuum motor (except the headlights) and I can watch if the guage stays put or not.

Oh, and I like your patch job. Mine looks the same way, except I have a new puke tank now ...

Pete76Shark

Actually the heater control valve works off of the temp part of the climate control.

As soon as you move the temp wheel off of its coldest setting the valve opens up and allows hot water to flow to the heater core.
The only thing the temp wheel does after that is to adjust the baffel inside the heater/ac box above the passengers feet.

I have had both situations where the vlave is stuck open and stuck closed. Since you have heat it is either stuck open or you have a vac problem. You will need a vacuum gague to see if you are getting any vac on the tube that goes to the valve. I am not sure which gets the vac, to turn the valve off or to turn it on.

I suggest:
http://www.northerntool.com/webapp/w...91590&R=391590
This is a great little hand vac pump and it will work for what you want.
Hook it up to the vale and see if it will open & close, if so then you got a vac problem in the tube or climate control inside the car.

BerniesVette

Do what most of us have done, put shutoff valves on both heater hoses. This positively stops all hot coolant from entering the heater core. The valve will allow some coolant into the heater core unless the max setting is selected. It is the only setting where the valve is supposed to be fully closed. I would replace the heater control valve and the vaccuum lines and still install shutoff valves on the heater hoses. I keep them closed thru the hot months and open them when the colder temps warrant. This works great and you get full benefit od A/C if you have it.
Bernie

rihwoods

I often wondered about that "max" a/c setting re the heat control valve....think that makes sense,considering the operation of the Temp Control lever.(in my case,78)..then,I hardly even use a/c,and never the heat.....

Roadster71

I have the opposite problem if you can believe it. I can't get any heat out of the wifes 82, but the air works fine.

BLACKHORSEVET

Hi y'all,
I want to install the shutoff valves.Can someone explain to me what kind of valves you used,and where is the best place to install them?
Somewhere in the hoses or directly into the waterpump and intake?Thanks

glen242

I used brass ball valves, the stock hose fittings on one end and black iron pipe nipples in the water pump and intake on the other end. The valves I used came from Lowe's or Home Depot. They have nice red (or Chevy Orange, depends upon how you look at it) handles and are 1/4 turn off to on.

BLACKHORSEVET

glen242
Thanks for the reply.I don't know if I have it straight though.Are you saying that the pipe nippels thread into the intake,waterpump,and then thread the ball valves into the nippels?This putting the valves
right at the block.You got to forgive me,I'm old.LOL

lucky76

I purchased mine at Autozone. You need one that is for the 5/8 inch hose and another for the 3/4 inch hose. They have both. Don't forget to get 4 small hose clamps also. Cut the hoses close to the vacuum valve cutoff and intall them there so you can tye wrap them together away from the exhaust manifold.

BLACKHORSEVET

Thanks everyone.Looks like a trip into town tomorrow.

78pacer

I replaced my heater control valve with a Dr. rebuild replacement for $22.00. While I was messing with the valve, It was a great opportunity to replace both heater hoses with nice new molded hoses. It was one of those, "While I'm at it's".
No more hot air pouring into the cabin around my feet.
Mike

bobs77vet

heres how i did mine, 3/8 "pipe fitting and ball valve in line with the smaller heater hose
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bootlegger2000

Hello gents.
I have looked at the wilcox and the other posted diagram. I have hooked up what i think is the way it is in both diagrams.
I have the vacuum on port 1
the 2 port is unused.
Port 3 i hooked up to the pancake switch on the drivers side of the plenum which has the spring on it. This is the only way i can get defrost.
With that being said the only way i can get the door on the passenger side to open is to take the hose off #3 port (that is working defrost)and put the line that is marked as port 4 on the diagram onto port 3. then the door opens and the vent works? I cant get them all to work correctly?
Any idea of what i may be doing wrong?

lvmyvt76

contact Willcox for help, he has diagrams for everything, or if you are lucky Alan will show you some pictures of his beautiful car!!!!! Come on Alan!