[Bob80Elcam]

It attaches to one of the heater hoses. The nipple where the vacuum hose attaches is loose. It rotates 360 degrees which I assume means it is broken and the part needs to be replaced.

 

[Tom Mobley]

heater control valve, cheap and easy to replace. cuts off water to the heater core when you've got the A/C on.

 

[Mike]

It's a heater shut off valve.
Called " Heater Vacuum Actuating Valve" by GM.

 

[Bob80Elcam]

Thanks Mike. That could be why my AC is not as cold as it should be. I will replace it. As always, I appreciate the help.

 

[Bob80Elcam]

Thanks to Tom too.