Who has a pic of the heater shut off valve on their car? I am trying to find the proper location before I cut my hoses to install this thing. Its on a 78 Pace car. Thank you!!

 

my assembly manual has a good diagram, it is on the 3/4" hose and is clipped just under and slightly right of the coolant tank.

 

I have 78 and am also very interested in a pic to make sure.

 

I have a pic of mine ,mounted under the coolant resivoir , trying to figure out photo bucket , give me some time

 

 

On my Vettes, all originals, the valve is more upright. Factory valve doesn't have any mounting bracket, it's just held in place by the heater hose(5/8" one) and just kinda hovers 3 or 4 inches above the frame rail.

 

Ditto here for my '76.

 

Jerry, here's a picture of the extra shutoff valve I installed in my heater hoses. I close the valves in the summer. Keeps the hot water from circulating through the heater. I was told it keeps some of the heat out of the cockpit. Seems to help a little. You can see the valve in the top hose. Have one in the bottom hose also, straight down from the top one. Not sure if this is what you're referring to, or the stock vacuum operated valve. The vacuum operated valve on my 77 is located just below the coolant tank.
KC

 

This is what I did to mine.

 

For now I am just going to put the stock valve back in. I finally located the vacuum hose for it (snipped off at the firewall). I am having to order some vacuum tees small enough to fit the replacement vacuum hoses I bought (they didnt come with the kit). If for some reason it doesnt work I am going to put a manual valve on it. I had a lot of cabin heat before. Trying to get as much of this mess cleaned up and function while I have the interior stripped out of the car. Oh, I finally found my AIM again today!!! It had slipped into a parts box

 

Thanks Basscat That is what I needed

 

I was just driving my vette the other day and getting annoyed at the hissing coming from the heater control valve plunger valve (located on the tiop of the heater box in the passenger side interior). It really gets to me that it is almost impossible to get the darn thing adjusted so that it keeps the valve closed to prevent hot water from getting into the heater core and subsequently the cabin. Many people solve this by putting in a second manual valve to shut off the water. I'm not a big fan of this solution because I don't like the look or having to go under the hood to open the valve.

And then it hit me....

The plunger valve has three outlets on it, one is the vacuum source, the other leads from the plunger valve to the water shutoff valve and the third is the exhaust port which is used to suck in air when the plunger is not fully depressed. The air coming in reduces the vacuum which allows the water shutoff valve to open. That hissing you hear is not GM reminding you to push the temperature lever to cold (yet again no matter who much you adjust it), it's air getting in and opening the valve. A slow leak translates into reduced vacuum which partially opens the water valve. You get the point.

If I could block the exhaust port, it wouldn't matter where the temp arm was. As long as the vacuum system works fine, the valve would be fully closed because it would receive initial vacuum and then not be able to release it. I initially considered just putting a vacuum plug on the exhaust, but then I would need to remove the glovebox to enable the heat each year.

What I'm going to do is to put a short length of vacuum hose on the exhaust port (nearest the plunger) and run it to a convenient spot under the dash. I can then plug/unplug it easily without getting out of the car. voila! Problem solved, and even cheaper than buying a manual valve as long as your system is working to start with.