[DAVID GAGNARD]

Ken;

I have seen these valves on many autos,but mostly GMs and mostly Caddys and Buicks,do not know why. They are mostly vacum operated but I have seen a few on older trucks that had the manuel choke type cable to operate.. All those I have seen were located on one hose only and very close to the firewall or heater box...I think they where put there for ease and convience rather than anything else....

You would need to check the flow direction of your heater hoses and I would think put the valve in the hose going into the heater box,not the hose coming out,that way you stop the flow before it gets to the box..

Hope this helps.....

David