B
bmotojoe
Guest
Is there always hot air blowing through your heater box? No matter what you do to resolve this problem it is always there? On the 1977 through 1982 Corvettes equipped with and I think without Air Conditioning there are two major components involved. There is the inline vacuum operated hot water shutoff valve that feeds hot water to the heater core and the vacuum shutoff valve that controls it. The inline hot water valve works as a ball valve when you move the heater control slide to the cold position the cable extends and in doing so moves an arm that pushes in the plunger spool of the vacuum shutoff valve sending vacuum to the inline hot water shutoff valve (The Vacuum Shutoff Valve Is Located On Top Of The Heaterbox). Over time the “O” rings on the spool dry out and vacuum bleeds by to the exhaust port of the vacuum shutoff valve never allowing enough vacuum to reach the inline hot water shutoff valve.
There are replacement valves available through most of the major vendors out there but the spring installed in them is to heavy for this applacation. They may work fine for 1969 through 1972 Corvette windshield wiper arm control valve but if used on the heater slide control side the spring is to heavy and the heater control slide will not stay in the cold position. After testing the inline heater control valve with a vacuum pump to make sure it held vacuum and was mechanically sound I removed the old spring from my old valve and after removing the heavy spring from the new valve I installed my old spring in the new valve. Once the vacuum shutoff valve was removed from the car it is a 10 minute repair.
Attached you will see how I did it.
Hope this helps,
Brian
View attachment 13627
There are replacement valves available through most of the major vendors out there but the spring installed in them is to heavy for this applacation. They may work fine for 1969 through 1972 Corvette windshield wiper arm control valve but if used on the heater slide control side the spring is to heavy and the heater control slide will not stay in the cold position. After testing the inline heater control valve with a vacuum pump to make sure it held vacuum and was mechanically sound I removed the old spring from my old valve and after removing the heavy spring from the new valve I installed my old spring in the new valve. Once the vacuum shutoff valve was removed from the car it is a 10 minute repair.
Attached you will see how I did it.
Hope this helps,
Brian
View attachment 13627