What is this piece for?

[Marcone]

http://www.pelicanparts.com/PartsLookup/HTML/944_2_USA_85_88_KATALOG/105-07-Frame3.htm

Part Number 29

We're rebuilding an engine right now and are missing some hose to go to the water pipe along the head. it seems that we're missing that piece.. what is it for .. cause we cant find it.. Just gonna end up bypassing it to get the car started.
HAHA

Marcone

[Techno Duck]

Heater control valve. Vacuum operated.. allows coolant flow to the heater core in the dash.

[Marcone]

Awesome..

so could that have been the reason why i had hot air all the time? cuz i was missing it?

[hpservertech]

Definatly. But also check for the clip that gets broke inside the car. It's by the pedals.

[Tidybuoy]

There's also a hard-plastic, small vacuum line that controls the heat. I'm not sure if it connect to this valve but the other end connects to the brake booster check valve. If this line is disconnected of gone, the heater stays on. Ask me how I lost 5lbs this summer (lol).