Do i need this valve? I have AC. If I do need it.. How does it work? IE then valve is closed how does it circulate the water vs when it is open? And what do you do for the line which used to go to the TB?

 

I'm not a TPI nor LT1 guru by any stretch, but I'll take a stab since nobody else did.

The valve only cuts coolant flow to the heater core when the AC is in the "max" position.

For the LT1, you should be able to block off the TB line. But, since I only have a fuzzy mental photo of a TPI system from my bud's car (who moved away 15 months ago), and even fuzzier of LT1, hopefully someone else will chime in with a better answer.

 

Yeah the valve is vacuum operated and opens and closes a coolent line. I was a bit mystified at its operation, that is until I dropped it and it started working again. It sticks... When you apply vauum (via test pump) the valve opens. On mine, if you release the vacuum and give it a tap it closes...
Whether or not I need it, I still do not know.. except that is will run without it.. SHould I have it.. dunno either.

 

If you are in a warmer climate, I would definitely keep it. If you are up north, dump it, you can do without it.

 

You don't "need" it.

The heater control applies vacuum to the valve in the "max" AC position to eliminate the flow to the heater core and "maximize" the cooling output of the AC.

If you use "max" AC, you might want to keep it. My car didn't have it, though.