Heater Shut-off valves

On the '82 the shut off valve closes when you turn the AC on. I don't know about the other years. That does not help when you are cruising with the tops off and your feet are roasting. The best thing I found is to put both valves in.  It keeps the hot water out of the heater core.  However just because you do this does not mean that some heat is not transferred to the heater core.  This is just a helps.  

Also a lot of heat seems to come through the firewall from the engine.

Just putting one did not seem to help as much as the two because the heat migrates up the water in the open hose.  Two seemed to be better but it could just be me. 

I close them in the spring.  You can mounted them so I could reach both of them from the top or I know one guy that did it where you have to go under the car for the lower one. 

I put mine so you can get at both from the top.

The bottom one is not much trouble to get at if the engine is cool.  If it is not.  Then no way I'm going to put my hand down there to turn it off. 

Part numbers for the valves at NAPA:  Sorry I forget which one is the top and which one is the bottom.  I do not even remember which is the input and output from the heater.  It was not important to me as I was putting in both of them.  

3/4 inch 660-1413 

5/8 inch 660-1414

Jim,