Mine opens when I turn on the heat.

 

I thought it was weird, maybe Someone who had the truck before has hooked the air lines up wrong... I'll have to investigate that because there is one more line that goes over to the brake master cylinder maybe they got switched or something...

 

Is it the stock valve? I can't say for sure wether or not they make normally open and normally closed heater valves for different vehicles but I do know they make both type valves for other applications. Might be worth checking.

 

Well I did a heater core flush today and filled it with CLR for about an hour, waiting to get some coolant or distilled water to refill it... The vacuum actuated valve in the line seems to work as far as opening and closing with vacuum, hopefully I get some heat now

 

What seems odd to me is that the heater control valve closes when I turn on the heat stopping coolant flow through the heater core... Is that rite??

 

I found another valve in pik n pull, it seems to work the same way as the one I have but I will definitely look into the different valves

 

I filled the heater core with CLR and let that soak for an hour, flushed it back and forth a couple more times afterward, and now I'm gettin some heat through the vents...

 

I'm goin on a longer drive thisevening and will see if heater valve allows core to stay warm and I didn't check to see if heater lines heat up at the same time as one another